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<li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en" class=""><span>Donate</span></a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=IPv4" title="You are encouraged to create an account and log in; however, it is not mandatory" class=""><span>Create account</span></a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:UserLogin&returnto=IPv4" title="You're encouraged to log in; however, it's not mandatory. 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data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Purpose" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Purpose"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Purpose</span> </div> </a> <ul id="toc-Purpose-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Addressing" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Addressing"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Addressing</span> </div> </a> <button aria-controls="toc-Addressing-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Addressing subsection</span> </button> <ul id="toc-Addressing-sublist" class="vector-toc-list"> <li id="toc-Address_representations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Address_representations"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Address representations</span> </div> </a> <ul id="toc-Address_representations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Allocation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Allocation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Allocation</span> </div> </a> <ul id="toc-Allocation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Special-use_addresses" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Special-use_addresses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Special-use addresses</span> </div> </a> <ul id="toc-Special-use_addresses-sublist" class="vector-toc-list"> <li id="toc-Private_networks" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Private_networks"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3.1</span> <span>Private networks</span> </div> </a> <ul id="toc-Private_networks-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Link-local_addressing" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Link-local_addressing"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.4</span> <span>Link-local addressing</span> </div> </a> <ul id="toc-Link-local_addressing-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Loopback" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Loopback"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.5</span> <span>Loopback</span> </div> </a> <ul id="toc-Loopback-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-First_and_last_subnet_addresses" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#First_and_last_subnet_addresses"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.6</span> <span>First and last subnet addresses</span> </div> </a> <ul id="toc-First_and_last_subnet_addresses-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Address_resolution" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Address_resolution"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.7</span> <span>Address resolution</span> </div> </a> <ul id="toc-Address_resolution-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Unnumbered_interface" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Unnumbered_interface"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.8</span> <span>Unnumbered interface</span> </div> </a> <ul id="toc-Unnumbered_interface-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Address_space_exhaustion" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Address_space_exhaustion"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Address space exhaustion</span> </div> </a> <ul id="toc-Address_space_exhaustion-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Packet_structure" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Packet_structure"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Packet structure</span> </div> </a> <button aria-controls="toc-Packet_structure-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Packet structure subsection</span> </button> <ul id="toc-Packet_structure-sublist" class="vector-toc-list"> <li id="toc-Header" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Header"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Header</span> </div> </a> <ul id="toc-Header-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Fragmentation_and_reassembly" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Fragmentation_and_reassembly"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Fragmentation and reassembly</span> </div> </a> <button aria-controls="toc-Fragmentation_and_reassembly-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Fragmentation and reassembly subsection</span> </button> <ul id="toc-Fragmentation_and_reassembly-sublist" class="vector-toc-list"> <li id="toc-Fragmentation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Fragmentation"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Fragmentation</span> </div> </a> <ul id="toc-Fragmentation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Reassembly" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Reassembly"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.2</span> <span>Reassembly</span> </div> </a> <ul id="toc-Reassembly-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Assistive_protocols" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Assistive_protocols"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Assistive protocols</span> </div> </a> <ul id="toc-Assistive_protocols-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">IPv4</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 49 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-49" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">49 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://ar.wikipedia.org/wiki/%D8%A8%D8%B1%D9%88%D8%AA%D9%88%D9%83%D9%88%D9%84_%D8%A7%D9%84%D8%A5%D9%86%D8%AA%D8%B1%D9%86%D8%AA_(%D8%A7%D9%84%D8%A5%D8%B5%D8%AF%D8%A7%D8%B1_%D8%A7%D9%84%D8%B1%D8%A7%D8%A8%D8%B9)" title="بروتوكول الإنترنت (الإصدار الرابع) – Arabic" lang="ar" hreflang="ar" data-title="بروتوكول الإنترنت (الإصدار الرابع)" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/IPv4" title="IPv4 – Azerbaijani" lang="az" hreflang="az" data-title="IPv4" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%86%E0%A6%87%E0%A6%AA%E0%A6%BF%E0%A6%AD%E0%A6%BF%E0%A7%AA" title="আইপিভি৪ – Bangla" lang="bn" hreflang="bn" data-title="আইপিভি৪" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/IPv4" title="IPv4 – Belarusian" lang="be" hreflang="be" data-title="IPv4" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/IPv4" title="IPv4 – Bulgarian" lang="bg" hreflang="bg" data-title="IPv4" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/IPv4" title="IPv4 – Bosnian" lang="bs" hreflang="bs" data-title="IPv4" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/IPv4" title="IPv4 – Czech" lang="cs" hreflang="cs" data-title="IPv4" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/IPv4" title="IPv4 – Danish" lang="da" hreflang="da" data-title="IPv4" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/IPv4" title="IPv4 – German" lang="de" hreflang="de" data-title="IPv4" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/IPv4" title="IPv4 – Estonian" lang="et" hreflang="et" data-title="IPv4" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/IPv4" title="IPv4 – Greek" lang="el" hreflang="el" data-title="IPv4" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/IPv4" title="IPv4 – Spanish" lang="es" hreflang="es" data-title="IPv4" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/IPv4" title="IPv4 – Basque" lang="eu" hreflang="eu" data-title="IPv4" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%BE%D8%B1%D9%88%D8%AA%DA%A9%D9%84_%D8%A7%DB%8C%D9%86%D8%AA%D8%B1%D9%86%D8%AA_%D9%86%D8%B3%D8%AE%D9%87_%DB%B4" title="پروتکل اینترنت نسخه ۴ – Persian" lang="fa" hreflang="fa" data-title="پروتکل اینترنت نسخه ۴" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/IPv4" title="IPv4 – French" lang="fr" hreflang="fr" data-title="IPv4" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Protocolo_IPv4" title="Protocolo IPv4 – Galician" lang="gl" hreflang="gl" data-title="Protocolo IPv4" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-gu mw-list-item"><a href="https://gu.wikipedia.org/wiki/IPv4" title="IPv4 – Gujarati" lang="gu" hreflang="gu" data-title="IPv4" data-language-autonym="ગુજરાતી" data-language-local-name="Gujarati" class="interlanguage-link-target"><span>ગુજરાતી</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/IPv4" title="IPv4 – Korean" lang="ko" hreflang="ko" data-title="IPv4" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/IPv4" title="IPv4 – Armenian" lang="hy" hreflang="hy" data-title="IPv4" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%87%E0%A4%82%E0%A4%9F%E0%A4%B0%E0%A4%A8%E0%A5%87%E0%A4%9F_%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A5%8B%E0%A4%9F%E0%A5%8B%E0%A4%95%E0%A5%89%E0%A4%B2_4" title="इंटरनेट प्रोटोकॉल 4 – Hindi" lang="hi" hreflang="hi" data-title="इंटरनेट प्रोटोकॉल 4" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/IPv4" title="IPv4 – Croatian" lang="hr" hreflang="hr" data-title="IPv4" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Alamat_IP_versi_4" title="Alamat IP versi 4 – Indonesian" lang="id" hreflang="id" data-title="Alamat IP versi 4" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/IPv4" title="IPv4 – Italian" lang="it" hreflang="it" data-title="IPv4" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/IPv4" title="IPv4 – Hebrew" lang="he" hreflang="he" data-title="IPv4" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/IPv4" title="IPv4 – Latvian" lang="lv" hreflang="lv" data-title="IPv4" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-ln mw-list-item"><a href="https://ln.wikipedia.org/wiki/IPv4" title="IPv4 – Lingala" lang="ln" hreflang="ln" data-title="IPv4" data-language-autonym="Lingála" data-language-local-name="Lingala" class="interlanguage-link-target"><span>Lingála</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/IPv4" title="IPv4 – Macedonian" lang="mk" hreflang="mk" data-title="IPv4" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%90%E0%B4%AA%E0%B4%BF%E0%B4%B5%E0%B4%BF4" title="ഐപിവി4 – Malayalam" lang="ml" hreflang="ml" data-title="ഐപിവി4" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/IPv4" title="IPv4 – Malay" lang="ms" hreflang="ms" data-title="IPv4" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/IPv4" title="IPv4 – Mongolian" lang="mn" hreflang="mn" data-title="IPv4" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Internet_Protocol_versie_4" title="Internet Protocol versie 4 – Dutch" lang="nl" hreflang="nl" data-title="Internet Protocol versie 4" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/IPv4" title="IPv4 – Japanese" lang="ja" hreflang="ja" data-title="IPv4" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/IPv4" title="IPv4 – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="IPv4" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/IPv4" title="IPv4 – Polish" lang="pl" hreflang="pl" data-title="IPv4" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/IPv4" title="IPv4 – Portuguese" lang="pt" hreflang="pt" data-title="IPv4" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/IPv4" title="IPv4 – Russian" lang="ru" hreflang="ru" data-title="IPv4" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/IPv4" title="IPv4 – Slovak" lang="sk" hreflang="sk" data-title="IPv4" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/IPv4" title="IPv4 – Serbian" lang="sr" hreflang="sr" data-title="IPv4" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Ipv4" title="Ipv4 – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Ipv4" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/IPv4" title="IPv4 – Finnish" lang="fi" hreflang="fi" data-title="IPv4" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/IPv4" title="IPv4 – Swedish" lang="sv" hreflang="sv" data-title="IPv4" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%87%E0%AE%A3%E0%AF%88%E0%AE%AF_%E0%AE%A8%E0%AF%86%E0%AE%B1%E0%AE%BF%E0%AE%AE%E0%AF%81%E0%AE%B1%E0%AF%88%E0%AE%AA%E0%AF%8D_%E0%AE%AA%E0%AE%A4%E0%AE%BF%E0%AE%AA%E0%AF%8D%E0%AE%AA%E0%AF%81_4" title="இணைய நெறிமுறைப் பதிப்பு 4 – Tamil" lang="ta" hreflang="ta" data-title="இணைய நெறிமுறைப் பதிப்பு 4" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/IPv4" title="IPv4 – Turkish" lang="tr" hreflang="tr" data-title="IPv4" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/IPv4" title="IPv4 – Ukrainian" lang="uk" hreflang="uk" data-title="IPv4" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/IPv4" title="IPv4 – Vietnamese" lang="vi" hreflang="vi" data-title="IPv4" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/IPv4" title="IPv4 – Wu" lang="wuu" hreflang="wuu" data-title="IPv4" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/IPv4" title="IPv4 – Yoruba" lang="yo" hreflang="yo" data-title="IPv4" data-language-autonym="Yorùbá" data-language-local-name="Yoruba" class="interlanguage-link-target"><span>Yorùbá</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/IPv4" title="IPv4 – Cantonese" lang="yue" hreflang="yue" data-title="IPv4" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/IPv4" title="IPv4 – Chinese" lang="zh" hreflang="zh" data-title="IPv4" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a 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Click to view the published version." rel="nofollow"><img alt="This article has been published in the peer-reviewed journal WikiJournal of Science (2022). Click to view the published version." src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Journal_Icon.svg/20px-Journal_Icon.svg.png" decoding="async" width="20" height="18" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Journal_Icon.svg/30px-Journal_Icon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/Journal_Icon.svg/40px-Journal_Icon.svg.png 2x" data-file-width="525" data-file-height="479" /></a></span></div></div> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Fourth version of the Internet Protocol</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox vevent" style="width:26em;"><caption class="infobox-title summary">Internet Protocol version 4</caption><tbody><tr><td colspan="2" class="infobox-subheader"><a href="/wiki/Protocol_stack" title="Protocol stack">Protocol stack</a></td></tr><tr><td colspan="2" class="infobox-image"><span class="skin-invert-image" typeof="mw:File"><a href="/wiki/File:IPv4_Packet-en.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/60/IPv4_Packet-en.svg/250px-IPv4_Packet-en.svg.png" decoding="async" width="250" height="114" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/60/IPv4_Packet-en.svg/375px-IPv4_Packet-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/60/IPv4_Packet-en.svg/500px-IPv4_Packet-en.svg.png 2x" data-file-width="936" data-file-height="427" /></a></span><div class="infobox-caption">IPv4 packet</div></td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;">Abbreviation</th><td class="infobox-data">IPv4</td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;">Purpose</th><td class="infobox-data"><a href="/wiki/Internetworking" title="Internetworking">Internetworking</a> protocol</td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;">Developer(s)</th><td class="infobox-data"><a href="/wiki/DARPA" title="DARPA">DARPA</a></td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;">Introduction</th><td class="infobox-data">1981<span class="noprint">; 43 years ago</span><span style="display:none"> (<span class="bday dtstart published updated">1981</span>)</span></td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;">Influenced</th><td class="infobox-data"><a href="/wiki/IPv6" title="IPv6">IPv6</a></td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;"><a href="/wiki/OSI_model" title="OSI model">OSI layer</a></th><td class="infobox-data"><a href="/wiki/Network_layer" title="Network layer">Network layer</a></td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap; width:25%;"><a href="/wiki/Request_for_Comments" title="Request for Comments">RFC(s)</a></th><td class="infobox-data"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output 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.cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc791">791</a></td></tr></tbody></table> <style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist 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.sidebar-title-with-pretitle{background:transparent!important}html.skin-theme-clientpref-night .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-list-title,html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media print{body.ns-0 .mw-parser-output .sidebar{display:none!important}}</style><table class="sidebar nomobile nowraplinks hlist"><tbody><tr><th class="sidebar-title"><a href="/wiki/Internet_protocol_suite" title="Internet protocol suite">Internet protocol suite</a></th></tr><tr><th class="sidebar-heading"> <a href="/wiki/Application_layer" title="Application layer">Application layer</a></th></tr><tr><td class="sidebar-content"> <ul><li><a href="/wiki/Border_Gateway_Protocol" title="Border Gateway Protocol">BGP</a></li> <li><a href="/wiki/Dynamic_Host_Configuration_Protocol" title="Dynamic Host Configuration Protocol">DHCP</a> (<a href="/wiki/DHCPv6" title="DHCPv6">v6</a>)</li> <li><a href="/wiki/Domain_Name_System" title="Domain Name System">DNS</a></li> <li><a href="/wiki/File_Transfer_Protocol" title="File Transfer Protocol">FTP</a></li> <li><a href="/wiki/HTTP" title="HTTP">HTTP</a> (<a href="/wiki/HTTP/3" title="HTTP/3">HTTP/3</a>)</li> <li><a href="/wiki/HTTPS" title="HTTPS">HTTPS</a></li> <li><a href="/wiki/Internet_Message_Access_Protocol" title="Internet Message Access Protocol">IMAP</a></li> <li><a href="/wiki/IRC" title="IRC">IRC</a></li> <li><a href="/wiki/Lightweight_Directory_Access_Protocol" title="Lightweight Directory Access Protocol">LDAP</a></li> <li><a href="/wiki/Media_Gateway_Control_Protocol" title="Media Gateway Control Protocol">MGCP</a></li> <li><a href="/wiki/MQTT" title="MQTT">MQTT</a></li> <li><a href="/wiki/Network_News_Transfer_Protocol" title="Network News Transfer Protocol">NNTP</a></li> <li><a href="/wiki/Network_Time_Protocol" title="Network Time Protocol">NTP</a></li> <li><a href="/wiki/Open_Shortest_Path_First" title="Open Shortest Path First">OSPF</a></li> <li><a href="/wiki/Post_Office_Protocol" title="Post Office Protocol">POP</a></li> <li><a href="/wiki/Precision_Time_Protocol" title="Precision Time Protocol">PTP</a></li> <li><a href="/wiki/Open_Network_Computing_Remote_Procedure_Call" class="mw-redirect" title="Open Network Computing Remote Procedure Call">ONC/RPC</a></li> <li><a href="/wiki/Real-time_Transport_Protocol" title="Real-time Transport Protocol">RTP</a></li> <li><a href="/wiki/Real_Time_Streaming_Protocol" class="mw-redirect" title="Real Time Streaming Protocol">RTSP</a></li> <li><a href="/wiki/Routing_Information_Protocol" title="Routing Information Protocol">RIP</a></li> <li><a href="/wiki/Session_Initiation_Protocol" title="Session Initiation Protocol">SIP</a></li> <li><a href="/wiki/Simple_Mail_Transfer_Protocol" title="Simple Mail Transfer Protocol">SMTP</a></li> <li><a href="/wiki/Simple_Network_Management_Protocol" title="Simple Network Management Protocol">SNMP</a></li> <li><a href="/wiki/Secure_Shell" title="Secure Shell">SSH</a></li> <li><a href="/wiki/Telnet" title="Telnet">Telnet</a></li> <li><a href="/wiki/Transport_Layer_Security" title="Transport Layer Security">TLS/SSL</a></li> <li><a href="/wiki/XMPP" title="XMPP">XMPP</a></li> <li><a href="/wiki/Category:Application_layer_protocols" title="Category:Application layer protocols"><i>more...</i></a></li></ul></td> </tr><tr><th class="sidebar-heading"> <a href="/wiki/Transport_layer" title="Transport layer">Transport layer</a></th></tr><tr><td class="sidebar-content"> <ul><li><a href="/wiki/Transmission_Control_Protocol" title="Transmission Control Protocol">TCP</a></li> <li><a href="/wiki/User_Datagram_Protocol" title="User Datagram Protocol">UDP</a></li> <li><a href="/wiki/Datagram_Congestion_Control_Protocol" title="Datagram Congestion Control Protocol">DCCP</a></li> <li><a href="/wiki/Stream_Control_Transmission_Protocol" title="Stream Control Transmission Protocol">SCTP</a></li> <li><a href="/wiki/Resource_Reservation_Protocol" title="Resource Reservation Protocol">RSVP</a></li> <li><a href="/wiki/QUIC" title="QUIC">QUIC</a></li> <li><a href="/wiki/Category:Transport_layer_protocols" title="Category:Transport layer protocols"><i>more...</i></a></li></ul></td> </tr><tr><th class="sidebar-heading"> <a href="/wiki/Internet_layer" title="Internet layer">Internet layer</a></th></tr><tr><td class="sidebar-content"> <ul><li><a href="/wiki/Internet_Protocol" title="Internet Protocol">IP</a> <ul><li><a class="mw-selflink selflink">v4</a></li> <li><a href="/wiki/IPv6" title="IPv6">v6</a></li></ul></li> <li><a href="/wiki/Internet_Control_Message_Protocol" title="Internet Control Message Protocol">ICMP</a> (<a href="/wiki/ICMPv6" title="ICMPv6">v6</a>)</li> <li><a href="/wiki/Neighbor_Discovery_Protocol" title="Neighbor Discovery Protocol">NDP</a></li> <li><a href="/wiki/Explicit_Congestion_Notification" title="Explicit Congestion Notification">ECN</a></li> <li><a href="/wiki/Internet_Group_Management_Protocol" title="Internet Group Management Protocol">IGMP</a></li> <li><a href="/wiki/IPsec" title="IPsec">IPsec</a></li> <li><a href="/wiki/Category:Internet_layer_protocols" title="Category:Internet layer protocols"><i>more...</i></a></li></ul></td> </tr><tr><th class="sidebar-heading"> <a href="/wiki/Link_layer" title="Link layer">Link layer</a></th></tr><tr><td class="sidebar-content"> <ul><li><a href="/wiki/Address_Resolution_Protocol" title="Address Resolution Protocol">ARP</a></li> <li><a href="/wiki/Tunneling_protocol" title="Tunneling protocol">Tunnels</a></li> <li><a href="/wiki/Point-to-Point_Protocol" title="Point-to-Point Protocol">PPP</a></li> <li><a href="/wiki/Medium_access_control" title="Medium access control">MAC</a></li> <li><a href="/wiki/Category:Link_protocols" title="Category:Link protocols"><i>more...</i></a></li></ul></td> </tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Internet_protocol_suite" title="Template:Internet protocol suite"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Internet_protocol_suite" title="Template talk:Internet protocol suite"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Internet_protocol_suite" title="Special:EditPage/Template:Internet protocol suite"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <p><b>Internet Protocol version 4</b> (<b>IPv4</b>) is the first version of the <a href="/wiki/Internet_Protocol" title="Internet Protocol">Internet Protocol</a> (IP) as a standalone specification. It is one of the core protocols of standards-based <a href="/wiki/Internetworking" title="Internetworking">internetworking</a> methods in the <a href="/wiki/Internet" title="Internet">Internet</a> and other <a href="/wiki/Packet-switched" class="mw-redirect" title="Packet-switched">packet-switched</a> networks. IPv4 was the first version deployed for production on <a href="/wiki/SATNET" title="SATNET">SATNET</a> in 1982 and on the <a href="/wiki/ARPANET" title="ARPANET">ARPANET</a> in January 1983. It is still used to route most <a href="/wiki/Internet_traffic" title="Internet traffic">Internet traffic</a> today,<sup id="cite_ref-:0_1-0" class="reference"><a href="#cite_note-:0-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> even with the ongoing deployment of <a href="/wiki/IPv6" title="IPv6">Internet Protocol version 6</a> (IPv6),<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> its successor. </p><p>IPv4 uses a <a href="/wiki/32-bit" class="mw-redirect" title="32-bit">32-bit</a> address space which provides 4,294,967,296 (2<sup>32</sup>) unique addresses, but large blocks are reserved for special networking purposes.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-rfc6890_4-0" class="reference"><a href="#cite_note-rfc6890-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Earlier versions of TCP/IP were a combined specification through TCP/IPv3. With IPv4, the Internet Protocol became a separate specification.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>Internet Protocol version 4 is described in <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a> publication RFC 791 (September 1981), replacing an earlier definition of January 1980 (RFC 760). In March 1982, the US Department of Defense decided on the <a href="/wiki/Internet_Protocol_Suite" class="mw-redirect" title="Internet Protocol Suite">Internet Protocol Suite</a> (TCP/IP) as the standard for all military <a href="/wiki/Computer_network" title="Computer network">computer networking</a>.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Purpose">Purpose</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=2" title="Edit section: Purpose"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Internet Protocol is the protocol that defines and enables <a href="/wiki/Internetwork" class="mw-redirect" title="Internetwork">internetworking</a> at the <a href="/wiki/Internet_layer" title="Internet layer">internet layer</a> of the Internet Protocol Suite. In essence it forms the Internet. It uses a logical addressing system and performs <i>routing</i>, which is the forwarding of packets from a source host to the next router that is one hop closer to the intended destination host on another network. </p><p>IPv4 is a <a href="/wiki/Connectionless" class="mw-redirect" title="Connectionless">connectionless</a> protocol, and operates on a <a href="/wiki/Best-effort_delivery" title="Best-effort delivery">best-effort delivery</a> model, in that it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an <a href="/wiki/Upper_layer_protocol" class="mw-redirect" title="Upper layer protocol">upper layer</a> transport protocol, such as the <a href="/wiki/Transmission_Control_Protocol" title="Transmission Control Protocol">Transmission Control Protocol</a> (TCP). </p> <div class="mw-heading mw-heading2"><h2 id="Addressing"><span class="anchor" id="IPv4_Addressing"></span>Addressing</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=3" title="Edit section: Addressing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For broader coverage of this topic, see <a href="/wiki/IP_address" title="IP address">IP address</a>.</div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:IPv4_address_structure_and_writing_systems-en.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/66/IPv4_address_structure_and_writing_systems-en.svg/300px-IPv4_address_structure_and_writing_systems-en.svg.png" decoding="async" width="300" height="102" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/66/IPv4_address_structure_and_writing_systems-en.svg/450px-IPv4_address_structure_and_writing_systems-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/66/IPv4_address_structure_and_writing_systems-en.svg/600px-IPv4_address_structure_and_writing_systems-en.svg.png 2x" data-file-width="1138" data-file-height="386" /></a><figcaption>Decomposition of the quad-dotted IPv4 address representation to its <a href="/wiki/Binary_numeral_system" class="mw-redirect" title="Binary numeral system">binary</a> value</figcaption></figure> <p>IPv4 uses 32-bit addresses which limits the <a href="/wiki/Address_space" title="Address space">address space</a> to <span style="white-space:nowrap">4<span style="margin-left:0.25em">294</span><span style="margin-left:0.25em">967</span><span style="margin-left:0.25em">296</span></span> (2<sup>32</sup>) addresses. </p><p>IPv4 reserves special address blocks for <a href="/wiki/Private_network" title="Private network">private networks</a> (2<sup>24</sup> + 2<sup>20</sup> + 2<sup>16</sup> ≈ 18 million addresses) and <a href="/wiki/Multicast" title="Multicast">multicast</a> addresses (2<sup>28</sup> ≈ 268 million addresses). </p> <div class="mw-heading mw-heading3"><h3 id="Address_representations">Address representations</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=4" title="Edit section: Address representations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>IPv4 addresses may be represented in any notation expressing a 32-bit integer value. They are most often written in <a href="/wiki/Dot-decimal_notation" title="Dot-decimal notation">dot-decimal notation</a>, which consists of four <a href="/wiki/Octet_(computing)" title="Octet (computing)">octets</a> of the address expressed individually in <a href="/wiki/Decimal" title="Decimal">decimal</a> numbers and separated by <a href="/wiki/Full_stop" title="Full stop">periods</a>. </p><p>For example, the quad-dotted IP address in the illustration (<i><span class="ipaddr"><span style="padding-right: 1px;">172.16.254.1</span></span></i>) represents the 32-bit <a href="/wiki/Decimal" title="Decimal">decimal</a> number 2886794753, which in <a href="/wiki/Hexadecimal" title="Hexadecimal">hexadecimal</a> format is 0xAC10FE01. </p><p><a href="/wiki/CIDR_notation" class="mw-redirect" title="CIDR notation">CIDR notation</a> combines the address with its routing prefix in a compact format, in which the address is followed by a slash character (/) and the count of leading consecutive <i>1</i> bits in the routing prefix (subnet mask). </p><p>Other address representations were in common use when <a href="/wiki/Classful_network" title="Classful network">classful networking</a> was practiced. For example, the <a href="/wiki/Loopback" title="Loopback">loopback</a> address <i><span class="ipaddr"><span style="padding-right: 1px;">127.0.0.1</span></span></i> was commonly written as <i><span class="ipaddr"><span style="padding-right: 1px;">127.1</span></span></i>, given that it belongs to a class-A network with eight bits for the network mask and 24 bits for the host number. When fewer than four numbers were specified in the address in dotted notation, the last value was treated as an integer of as many bytes as are required to fill out the address to four octets. Thus, the address <i><span class="ipaddr"><span style="padding-right: 1px;">127.65530</span></span></i> is equivalent to <i><span class="ipaddr"><span style="padding-right: 1px;">127.0.255.250</span></span></i>. </p> <div class="mw-heading mw-heading3"><h3 id="Allocation"><span class="anchor" id="Allocation"></span>Allocation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=5" title="Edit section: Allocation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the original design of IPv4, an IP address was divided into two parts: the network identifier was the most significant octet of the address, and the host identifier was the rest of the address. The latter was also called the <i>rest field</i>. This structure permitted a maximum of 256 network identifiers, which was quickly found to be inadequate. </p><p>To overcome this limit, the most-significant address octet was redefined in 1981 to create <i>network classes</i>, in a system which later became known as <i>classful</i> networking. The revised system defined five classes. Classes A, B, and C had different bit lengths for network identification. The rest of the address was used as previously to identify a host within a network. Because of the different sizes of fields in different classes, each network class had a different capacity for addressing hosts. In addition to the three classes for addressing hosts, Class D was defined for <a href="/wiki/Multicast" title="Multicast">multicast</a> addressing and Class E was reserved for future applications. </p><p>Dividing existing classful networks into subnets began in 1985 with the publication of <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc950">950</a>. This division was made more flexible with the introduction of variable-length subnet masks (VLSM) in <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1109">1109</a> in 1987. In 1993, based on this work, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1517">1517</a> introduced <a href="/wiki/Classless_Inter-Domain_Routing" title="Classless Inter-Domain Routing">Classless Inter-Domain Routing</a> (CIDR),<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> which expressed the number of bits (from the <a href="/wiki/Most_significant_bit" class="mw-redirect" title="Most significant bit">most significant</a>) as, for instance, <i><span class="ipaddr"><span style="padding-right: 1px;">/24</span></span></i>, and the class-based scheme was dubbed <i>classful</i>, by contrast. CIDR was designed to permit repartitioning of any address space so that smaller or larger blocks of addresses could be allocated to users. The hierarchical structure created by CIDR is managed by the <a href="/wiki/Internet_Assigned_Numbers_Authority" title="Internet Assigned Numbers Authority">Internet Assigned Numbers Authority</a> (IANA) and the <a href="/wiki/Regional_Internet_registries" class="mw-redirect" title="Regional Internet registries">regional Internet registries</a> (RIRs). Each RIR maintains a publicly searchable <a href="/wiki/WHOIS" title="WHOIS">WHOIS</a> database that provides information about IP address assignments. </p> <div class="mw-heading mw-heading3"><h3 id="Special-use_addresses">Special-use addresses</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=6" title="Edit section: Special-use addresses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a> (IETF) and IANA have restricted from general use various <a href="/wiki/Reserved_IP_addresses" title="Reserved IP addresses">reserved IP addresses</a> for special purposes.<sup id="cite_ref-rfc6890_4-1" class="reference"><a href="#cite_note-rfc6890-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Notably these addresses are used for <a href="/wiki/Multicast" title="Multicast">multicast</a> traffic and to provide addressing space for unrestricted uses on private networks. </p> <dl><dd><table class="wikitable sortable"> <caption>Special address blocks </caption> <tbody><tr> <th>Address block </th> <th>Address range </th> <th>Number of addresses </th> <th>Scope </th> <th>Description </th></tr> <tr> <td>0.0.0.0/8 </td> <td>0.0.0.0–0.255.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7007167772160000000♠"></span>16<span style="margin-left:.25em;">777</span><span style="margin-left:.25em;">216</span></span> </td> <td>Software </td> <td>Current (local, "this") network<sup id="cite_ref-rfc6890_4-2" class="reference"><a href="#cite_note-rfc6890-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>10.0.0.0/8 </td> <td>10.0.0.0–10.255.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7007167772160000000♠"></span>16<span style="margin-left:.25em;">777</span><span style="margin-left:.25em;">216</span></span> </td> <td>Private network </td> <td>Used for local communications within a private network<sup id="cite_ref-rfc1918_8-0" class="reference"><a href="#cite_note-rfc1918-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>100.64.0.0/10 </td> <td>100.64.0.0–100.127.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7006419430400000000♠"></span>4<span style="margin-left:.25em;">194</span><span style="margin-left:.25em;">304</span></span> </td> <td>Private network </td> <td><a href="/wiki/IPv4_shared_address_space" title="IPv4 shared address space">Shared address space</a><sup id="cite_ref-rfc6598_9-0" class="reference"><a href="#cite_note-rfc6598-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> for communications between a service provider and its subscribers when using a <a href="/wiki/Carrier-grade_NAT" title="Carrier-grade NAT">carrier-grade NAT</a> </td></tr> <tr> <td>127.0.0.0/8 </td> <td>127.0.0.0–127.255.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7007167772160000000♠"></span>16<span style="margin-left:.25em;">777</span><span style="margin-left:.25em;">216</span></span> </td> <td>Host </td> <td>Used for <a href="/wiki/Loopback_address" class="mw-redirect" title="Loopback address">loopback addresses</a> to the local host<sup id="cite_ref-rfc6890_4-3" class="reference"><a href="#cite_note-rfc6890-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>169.254.0.0/16 </td> <td>169.254.0.0–169.254.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7004655360000000000♠"></span>65<span style="margin-left:.25em;">536</span></span> </td> <td>Subnet </td> <td>Used for <a href="/wiki/Link-local_address" title="Link-local address">link-local addresses</a><sup id="cite_ref-rfc3927_10-0" class="reference"><a href="#cite_note-rfc3927-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> between two hosts on a single link when no IP address is otherwise specified, such as would have normally been retrieved from a <a href="/wiki/DHCP" class="mw-redirect" title="DHCP">DHCP</a> server </td></tr> <tr> <td>172.16.0.0/12 </td> <td>172.16.0.0–172.31.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7006104857600000000♠"></span>1<span style="margin-left:.25em;">048</span><span style="margin-left:.25em;">576</span></span> </td> <td>Private network </td> <td>Used for local communications within a private network<sup id="cite_ref-rfc1918_8-1" class="reference"><a href="#cite_note-rfc1918-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>192.0.0.0/24 </td> <td>192.0.0.0–192.0.0.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7002256000000000000♠"></span>256</span> </td> <td>Private network </td> <td>IETF Protocol Assignments, <a href="/wiki/DS-Lite" class="mw-redirect" title="DS-Lite">DS-Lite</a> (/29)<sup id="cite_ref-rfc6890_4-4" class="reference"><a href="#cite_note-rfc6890-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>192.0.2.0/24 </td> <td>192.0.2.0–192.0.2.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7002256000000000000♠"></span>256</span> </td> <td>Documentation </td> <td>Assigned as TEST-NET-1, documentation and examples<sup id="cite_ref-rfc5737_11-0" class="reference"><a href="#cite_note-rfc5737-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>192.88.99.0/24 </td> <td>192.88.99.0–192.88.99.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7002256000000000000♠"></span>256</span> </td> <td>Internet </td> <td>Reserved.<sup id="cite_ref-rfc7526_12-0" class="reference"><a href="#cite_note-rfc7526-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> Formerly used for <a href="/wiki/6to4" title="6to4">IPv6 to IPv4</a> relay<sup id="cite_ref-rfc3068_13-0" class="reference"><a href="#cite_note-rfc3068-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> (included <a href="/wiki/IPv6" title="IPv6">IPv6</a> address block <a href="/wiki/IPv6_address#Special_addresses" title="IPv6 address">2002::/16</a>). </td></tr> <tr> <td>192.168.0.0/16 </td> <td>192.168.0.0–192.168.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7004655360000000000♠"></span>65<span style="margin-left:.25em;">536</span></span> </td> <td>Private network </td> <td>Used for local communications within a private network<sup id="cite_ref-rfc1918_8-2" class="reference"><a href="#cite_note-rfc1918-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>198.18.0.0/15 </td> <td>198.18.0.0–198.19.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7005131072000000000♠"></span>131<span style="margin-left:.25em;">072</span></span> </td> <td>Private network </td> <td>Used for benchmark testing of inter-network communications between two separate subnets<sup id="cite_ref-rfc2544_14-0" class="reference"><a href="#cite_note-rfc2544-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>198.51.100.0/24 </td> <td>198.51.100.0–198.51.100.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7002256000000000000♠"></span>256</span> </td> <td>Documentation </td> <td>Assigned as TEST-NET-2, documentation and examples<sup id="cite_ref-rfc5737_11-1" class="reference"><a href="#cite_note-rfc5737-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>203.0.113.0/24 </td> <td>203.0.113.0–203.0.113.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7002256000000000000♠"></span>256</span> </td> <td>Documentation </td> <td>Assigned as TEST-NET-3, documentation and examples<sup id="cite_ref-rfc5737_11-2" class="reference"><a href="#cite_note-rfc5737-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>224.0.0.0/4 </td> <td>224.0.0.0–239.255.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7008268435456000000♠"></span>268<span style="margin-left:.25em;">435</span><span style="margin-left:.25em;">456</span></span> </td> <td>Internet </td> <td>In use for <a href="/wiki/IP_multicast" title="IP multicast">multicast</a><sup id="cite_ref-rfc5771_15-0" class="reference"><a href="#cite_note-rfc5771-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> (former Class D network) </td></tr> <tr> <td>233.252.0.0/24 </td> <td>233.252.0.0–233.252.0.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7002256000000000000♠"></span>256</span> </td> <td>Documentation </td> <td>Assigned as MCAST-TEST-NET, documentation and examples (Note that this is part of the above multicast space.)<sup id="cite_ref-rfc5771_15-1" class="reference"><a href="#cite_note-rfc5771-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-rfc6676_16-0" class="reference"><a href="#cite_note-rfc6676-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td>240.0.0.0/4 </td> <td>240.0.0.0–255.255.255.254 </td> <td align="right"><span class="nowrap"><span data-sort-value="7008268435455000000♠"></span>268<span style="margin-left:.25em;">435</span><span style="margin-left:.25em;">455</span></span> </td> <td>Internet </td> <td>Reserved for future use<sup id="cite_ref-rfc3232_17-0" class="reference"><a href="#cite_note-rfc3232-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> (former Class E network) </td></tr> <tr> <td>255.255.255.255/32 </td> <td>255.255.255.255 </td> <td align="right"><span class="nowrap"><span data-sort-value="7000100000000000000♠"></span>1</span> </td> <td>Subnet </td> <td>Reserved for the "limited <a href="/wiki/Broadcast_address" title="Broadcast address">broadcast</a>" destination address<sup id="cite_ref-rfc6890_4-5" class="reference"><a href="#cite_note-rfc6890-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </td></tr></tbody></table></dd></dl> <div class="mw-heading mw-heading4"><h4 id="Private_networks">Private networks</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=7" title="Edit section: Private networks"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Of the approximately four billion addresses defined in IPv4, about 18 million addresses in three ranges are reserved for use in private networks. Packets addresses in these ranges are not routable in the public Internet; they are ignored by all public routers. Therefore, private hosts cannot directly communicate with public networks, but require <a href="/wiki/Network_address_translation" title="Network address translation">network address translation</a> at a routing gateway for this purpose. </p> <dl><dd><table class="wikitable"> <caption>Reserved private IPv4 network ranges<sup id="cite_ref-rfc1918_8-3" class="reference"><a href="#cite_note-rfc1918-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </caption> <tbody><tr> <th>Name</th> <th><a href="/wiki/CIDR" class="mw-redirect" title="CIDR">CIDR</a> block</th> <th>Address range</th> <th>Number of<br />addresses</th> <th><i><a href="/wiki/Classful" class="mw-redirect" title="Classful">Classful</a></i> description </th></tr> <tr> <td>24-bit block</td> <td>10.0.0.0/8</td> <td>10.0.0.0 – 10.255.255.255</td> <td align="right"><span class="nowrap"><span data-sort-value="7007167772160000000♠"></span>16<span style="margin-left:.25em;">777</span><span style="margin-left:.25em;">216</span></span></td> <td>Single Class A </td></tr> <tr> <td>20-bit block</td> <td>172.16.0.0/12</td> <td>172.16.0.0 – 172.31.255.255</td> <td align="right"><span class="nowrap"><span data-sort-value="7006104857600000000♠"></span>1<span style="margin-left:.25em;">048</span><span style="margin-left:.25em;">576</span></span></td> <td>Contiguous range of 16 Class B blocks </td></tr> <tr> <td>16-bit block</td> <td>192.168.0.0/16</td> <td>192.168.0.0 – 192.168.255.255</td> <td align="right"><span class="nowrap"><span data-sort-value="7004655360000000000♠"></span>65<span style="margin-left:.25em;">536</span></span></td> <td>Contiguous range of 256 Class C blocks </td></tr></tbody></table></dd></dl> <p>Since two private networks, e.g., two branch offices, cannot directly interoperate via the public Internet, the two networks must be bridged across the Internet via a <a href="/wiki/Virtual_private_network" title="Virtual private network">virtual private network</a> (VPN) or an <a href="/wiki/IP_tunnel" title="IP tunnel">IP tunnel</a>, which <a href="/wiki/Encapsulation_(networking)" title="Encapsulation (networking)">encapsulates</a> packets, including their headers containing the private addresses, in a protocol layer during transmission across the public network. Additionally, encapsulated packets may be encrypted for transmission across public networks to secure the data. </p> <div class="mw-heading mw-heading3"><h3 id="Link-local_addressing">Link-local addressing</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=8" title="Edit section: Link-local addressing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>RFC 3927 defines the special address block 169.254.0.0/16 for link-local addressing. These addresses are only valid on the link (such as a local network segment or point-to-point connection) directly connected to a host that uses them. These addresses are not routable. Like private addresses, these addresses cannot be the source or destination of packets traversing the internet. These addresses are primarily used for address autoconfiguration (<a href="/wiki/Zeroconf" class="mw-redirect" title="Zeroconf">Zeroconf</a>) when a host cannot obtain an IP address from a DHCP server or other internal configuration methods. </p><p>When the address block was reserved, no standards existed for address autoconfiguration. <a href="/wiki/Microsoft" title="Microsoft">Microsoft</a> created an implementation called <a href="/wiki/Automatic_Private_IP_Addressing" class="mw-redirect" title="Automatic Private IP Addressing">Automatic Private IP Addressing</a> (APIPA), which was deployed on millions of machines and became a <a href="/wiki/De_facto_standard" title="De facto standard">de facto standard</a>. Many years later, in May 2005, the <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a> defined a formal standard in RFC 3927, entitled <i>Dynamic Configuration of IPv4 Link-Local Addresses</i>. </p> <div class="mw-heading mw-heading3"><h3 id="Loopback">Loopback</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=9" title="Edit section: Loopback"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Localhost" title="Localhost">Localhost</a></div> <p>The class A network <i><span class="ipaddr"><span style="padding-right: 1px;">127.0.0.0</span></span></i> (classless network <i><span class="ipaddr"><span style="padding-right: 1px;">127.0.0.0</span><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">8</span></span></i>) is reserved for <a href="/wiki/Loopback" title="Loopback">loopback</a>. IP packets whose source addresses belong to this network should never appear outside a host. Packets received on a non-loopback interface with a loopback source or destination address must be dropped. </p> <div class="mw-heading mw-heading3"><h3 id="First_and_last_subnet_addresses">First and last subnet addresses</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=10" title="Edit section: First and last subnet addresses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/IPv4_subnetting_reference" class="mw-redirect" title="IPv4 subnetting reference">IPv4 subnetting reference</a></div> <p>The first address in a subnet is used to identify the subnet itself. In this address all host bits are <i>0</i>. To avoid ambiguity in representation, this address is reserved.<sup id="cite_ref-" class="reference"><a href="#cite_note-"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> The last address has all host bits set to <i>1</i>. It is used as a local <a href="/wiki/Broadcast_address" title="Broadcast address">broadcast address</a> for sending messages to all devices on the subnet simultaneously. For networks of size <i><span class="ipaddr"><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">24</span></span></i> or larger, the broadcast address always ends in 255. </p><p>For example, in the subnet <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.5.0</span><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">24</span></span></i> (subnet mask <i><span class="ipaddr"><span style="padding-right: 1px;">255.255.255.0</span></span></i>) the identifier <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.5.0</span></span></i> is used to refer to the entire subnet. The broadcast address of the network is <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.5.255</span></span></i>. </p> <table class="wikitable" style="margin:left"> <tbody><tr> <th>Type</th> <th>Binary form</th> <th>Dot-decimal notation </th></tr> <tr> <td>Network space </td> <td><code>11000000.10101000.00000101.<span style="color:red">00000000</span></code> </td> <td>192.168.5.0 </td></tr> <tr> <td>Broadcast address </td> <td><code>11000000.10101000.00000101.<span style="color:red">11111111</span></code> </td> <td>192.168.5.255 </td></tr> <tr> <td colspan="3"><small>In red, is shown the host part of the IP address; the other part is the network prefix. The host gets inverted (logical NOT), but the network prefix remains intact.</small> </td></tr></tbody></table> <p>However, this does not mean that every address ending in 0 or 255 cannot be used as a host address. For example, in the <i><span class="ipaddr"><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">16</span></span></i> subnet <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.0.0</span><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">255.255.0.0</span></span></i>, which is equivalent to the address range <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.0.0</span></span></i>–<i><span class="ipaddr"><span style="padding-right: 1px;">192.168.255.255</span></span></i>, the broadcast address is <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.255.255</span></span></i>. One can use the following addresses for hosts, even though they end with 255: <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.1.255</span></span></i>, <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.2.255</span></span></i>, etc. Also, <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.0.0</span></span></i> is the network identifier and must not be assigned to an interface.<sup id="cite_ref-rfc1122_19-0" class="reference"><a href="#cite_note-rfc1122-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 31">: 31 </span></sup> The addresses <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.1.0</span></span></i>, <i><span class="ipaddr"><span style="padding-right: 1px;">192.168.2.0</span></span></i>, etc., may be assigned, despite ending with 0. </p><p>In the past, conflict between network addresses and broadcast addresses arose because some software used non-standard broadcast addresses with zeros instead of ones.<sup id="cite_ref-rfc1122_19-1" class="reference"><a href="#cite_note-rfc1122-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 66">: 66 </span></sup> </p><p>In networks smaller than <i><span class="ipaddr"><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">24</span></span></i>, broadcast addresses do not necessarily end with 255. For example, a CIDR subnet <i><span class="ipaddr"><span style="padding-right: 1px;">203.0.113.16</span><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">28</span></span></i> has the broadcast address <i><span class="ipaddr"><span style="padding-right: 1px;">203.0.113.31</span></span></i>. </p> <table class="wikitable" style="margin:left"> <tbody><tr> <th>Type</th> <th>Binary form</th> <th>Dot-decimal notation </th></tr> <tr> <td>Network space </td> <td><code>11001011.00000000.01110001.0001<span style="color:red">0000</span></code> </td> <td>203.0.113.16 </td></tr> <tr> <td>Broadcast address </td> <td><code>11001011.00000000.01110001.0001<span style="color:red">1111</span></code> </td> <td>203.0.113.31 </td></tr> <tr> <td colspan="3"><small>In red, is shown the host part of the IP address; the other part is the network prefix. The host gets inverted (logical NOT), but the network prefix remains intact.</small> </td></tr></tbody></table> <p>As a special case, a <i><span class="ipaddr"><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">31</span></span></i> network has capacity for just two hosts. These networks are typically used for point-to-point connections. There is no network identifier or broadcast address for these networks.<sup id="cite_ref-rfc3021_20-0" class="reference"><a href="#cite_note-rfc3021-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Address_resolution">Address resolution</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=11" title="Edit section: Address resolution"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Domain_Name_System" title="Domain Name System">Domain Name System</a></div> <p>Hosts on the <a href="/wiki/Internet" title="Internet">Internet</a> are usually known by names, e.g., www.example.com, not primarily by their IP address, which is used for routing and network interface identification. The use of domain names requires translating, called <i>resolving</i>, them to addresses and vice versa. This is analogous to looking up a phone number in a phone book using the recipient's name. </p><p>The translation between addresses and domain names is performed by the <a href="/wiki/Domain_Name_System" title="Domain Name System">Domain Name System</a> (DNS), a hierarchical, distributed naming system that allows for the subdelegation of <a href="/wiki/Namespace" title="Namespace">namespaces</a> to other DNS servers. </p> <div class="mw-heading mw-heading3"><h3 id="Unnumbered_interface">Unnumbered interface</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=12" title="Edit section: Unnumbered interface"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A unnumbered <a href="/wiki/Point-to-point_(telecommunications)" title="Point-to-point (telecommunications)">point-to-point</a> (PtP) link, also called a transit link, is a link that does not have an IP network or subnet number associated with it, but still has an IP address. First introduced in 1993,<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-rfc1716_22-0" class="reference"><a href="#cite_note-rfc1716-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-rfc1812_23-0" class="reference"><a href="#cite_note-rfc1812-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> Phil Karn from Qualcomm is credited as the original designer. </p><p>The purpose of a transit link is to <a href="/wiki/Router_(computing)" title="Router (computing)">route</a> <a href="/wiki/Datagram" title="Datagram">datagrams</a>. They are used to free IP addresses from a scarce IP address space or to reduce the management of assigning IP and configuration of interfaces. Previously, every link needed to dedicate a <i><span class="ipaddr"><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">31</span></span></i> or <i><span class="ipaddr"><span style="padding-right: 1px;">/</span><span style="padding-right: 1px;">30</span></span></i> subnet using 2 or 4 IP addresses per point-to-point link. When a link is unnumbered, a <i>router-id</i> is used, a single IP address borrowed from a defined (normally a <a href="/wiki/Loopback" title="Loopback">loopback</a>) interface. The same <i>router-id</i> can be used on multiple interfaces. </p><p>One of the disadvantages of unnumbered interfaces is that it is harder to do remote testing and management. </p> <div class="mw-heading mw-heading2"><h2 id="Address_space_exhaustion">Address space exhaustion</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=13" title="Edit section: Address space exhaustion"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/IPv4_address_exhaustion" title="IPv4 address exhaustion">IPv4 address exhaustion</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:IPv4_exhaustion_time_line-en.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/35/IPv4_exhaustion_time_line-en.svg/440px-IPv4_exhaustion_time_line-en.svg.png" decoding="async" width="440" height="144" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/35/IPv4_exhaustion_time_line-en.svg/660px-IPv4_exhaustion_time_line-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/35/IPv4_exhaustion_time_line-en.svg/880px-IPv4_exhaustion_time_line-en.svg.png 2x" data-file-width="676" data-file-height="222" /></a><figcaption>IPv4 address exhaustion timeline</figcaption></figure> <p>In the 1980s, it became apparent that the pool of available IPv4 addresses was depleting at a rate that was not initially anticipated in the original design of the network.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> The main market forces that accelerated address depletion included the rapidly growing number of Internet users, who increasingly used mobile computing devices, such as <a href="/wiki/Laptop_computers" class="mw-redirect" title="Laptop computers">laptop computers</a>, <a href="/wiki/Personal_digital_assistant" title="Personal digital assistant">personal digital assistants</a> (PDAs), and <a href="/wiki/Smart_phone" class="mw-redirect" title="Smart phone">smart phones</a> with IP data services. In addition, high-speed Internet access was based on always-on devices. The threat of exhaustion motivated the introduction of a number of remedial technologies, such as: </p> <ul><li><a href="/wiki/Classless_Inter-Domain_Routing" title="Classless Inter-Domain Routing">Classless Inter-Domain Routing</a> (CIDR), for smaller ISP allocations</li> <li><a href="#Unnumbered_interface">Unnumbered interfaces</a> removed the need for addresses on transit links.</li> <li><a href="/wiki/Network_address_translation" title="Network address translation">Network address translation</a> (NAT) removed the need for the <a href="/wiki/End-to-end_principle" title="End-to-end principle">end-to-end principle</a>.</li></ul> <p>By the mid-1990s, NAT was used pervasively in network access provider systems, along with strict usage-based allocation policies at the regional and local Internet registries. </p><p>The primary address pool of the Internet, maintained by IANA, was exhausted on 3 February 2011, when the last five blocks were allocated to the five <a href="/wiki/Regional_Internet_registry" title="Regional Internet registry">RIRs</a>.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> <a href="/wiki/APNIC" title="APNIC">APNIC</a> was the first RIR to exhaust its regional pool on 15 April 2011, except for a small amount of address space reserved for the transition technologies to IPv6, which is to be allocated under a restricted policy.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p><p>The long-term solution to address exhaustion was the 1998 specification of a new version of the Internet Protocol, <a href="/wiki/IPv6" title="IPv6">IPv6</a>.<sup id="cite_ref-rfc2460_29-0" class="reference"><a href="#cite_note-rfc2460-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> It provides a vastly increased address space, but also allows improved route aggregation across the Internet, and offers large subnetwork allocations of a minimum of 2<sup>64</sup> host addresses to end users. However, IPv4 is not directly interoperable with IPv6, so that IPv4-only hosts cannot directly communicate with IPv6-only hosts. With the phase-out of the <a href="/wiki/6bone" title="6bone">6bone</a> experimental network starting in 2004, permanent formal deployment of IPv6 commenced in 2006.<sup id="cite_ref-rfc3701_30-0" class="reference"><a href="#cite_note-rfc3701-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> Completion of <a href="/wiki/IPv6_deployment" title="IPv6 deployment">IPv6 deployment</a> is expected to take considerable time,<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> so that intermediate <a href="/wiki/IPv6_transition_mechanism" title="IPv6 transition mechanism">transition technologies</a> are necessary to permit hosts to participate in the Internet using both versions of the protocol. </p> <div class="mw-heading mw-heading2"><h2 id="Packet_structure">Packet structure</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=14" title="Edit section: Packet structure"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>An IP <a href="/wiki/Packet_(information_technology)" class="mw-redirect" title="Packet (information technology)">packet</a> consists of a header section and a data section. An IP packet has no data checksum or any other footer after the data section. Typically the <a href="/wiki/Link_layer" title="Link layer">link layer</a> encapsulates IP packets in frames with a CRC footer that detects most errors. Many <a href="/wiki/Transport_layer" title="Transport layer">transport-layer protocols</a> carried by IP also have their own error checking.<sup id="cite_ref-rfc1726_32-0" class="reference"><a href="#cite_note-rfc1726-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Location: §6.2">: §6.2 </span></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Header">Header</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=15" title="Edit section: Header"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The IPv4 packet header consists of 14 fields, of which 13 are required. The 14th field is optional and aptly named: options. The fields in the header are packed with the most significant byte first (<a href="/wiki/Network_byte_order" class="mw-redirect" title="Network byte order">network byte order</a>), and for the diagram and discussion, the most significant bits are considered to come first (<a href="/wiki/MSB0" class="mw-redirect" title="MSB0">MSB 0 bit numbering</a>). The most significant bit is numbered 0, so the version field is actually found in the four most significant bits of the first byte, for example. </p> <table class="wikitable" style="text-align: center; border: none;"> <caption>IPv4 header format </caption> <tbody><tr> <th style="min-width:42px; border-bottom:none; border-right:none;"><i>Offset</i> </th> <th style="border-left:none;"><a href="/wiki/Octet_(computing)" title="Octet (computing)">Octet</a> </th> <th colspan="8">0 </th> <th colspan="8">1 </th> <th colspan="8">2 </th> <th colspan="8">3 </th></tr> <tr> <th style="min-width: 42px;border-top: none;">Octet </th> <th style="min-width: 42px;"><a href="/wiki/Bit" title="Bit">Bit</a> </th> <th style="min-width:11px;">0 </th> <th style="min-width:11px;">1 </th> <th style="min-width:11px;">2 </th> <th style="min-width:11px;">3 </th> <th style="min-width:11px;">4 </th> <th style="min-width:11px;">5 </th> <th style="min-width:11px;">6 </th> <th style="min-width:11px;">7 </th> <th style="min-width:11px;">8 </th> <th style="min-width:11px;">9 </th> <th style="min-width:16px;">10 </th> <th style="min-width:16px;">11 </th> <th style="min-width:16px;">12 </th> <th style="min-width:16px;">13 </th> <th style="min-width:16px;">14 </th> <th style="min-width:16px;">15 </th> <th style="min-width:16px;">16 </th> <th style="min-width:16px;">17 </th> <th style="min-width:16px;">18 </th> <th style="min-width:16px;">19 </th> <th style="min-width:16px;">20 </th> <th style="min-width:16px;">21 </th> <th style="min-width:16px;">22 </th> <th style="min-width:16px;">23 </th> <th style="min-width:16px;">24 </th> <th style="min-width:16px;">25 </th> <th style="min-width:16px;">26 </th> <th style="min-width:16px;">27 </th> <th style="min-width:16px;">28 </th> <th style="min-width:16px;">29 </th> <th style="min-width:16px;">30 </th> <th style="min-width:16px;">31 </th></tr> <tr> <th style="width:35px;">0 </th> <th style="width:30px;">0 </th> <td colspan="4"><i><a href="#Version">Version</a><span class="nowrap"> </span>(4)</i> </td> <td colspan="4"><i><a href="#IHL">IHL</a></i> </td> <td colspan="6"><i><a href="#DSCP">DSCP</a></i> </td> <td colspan="2"><i><a href="#ECN">ECN</a></i> </td> <td colspan="16"><i><a href="#Total_Length">Total Length</a></i> </td></tr> <tr> <th style="width:35px;">4 </th> <th style="width:30px;">32 </th> <td colspan="16"><i><a href="#Identification">Identification</a></i> </td> <td colspan="3"><i><a href="#Flags">Flags</a></i> </td> <td colspan="13"><i><a href="#Fragment_offset">Fragment Offset</a></i> </td></tr> <tr> <th style="width:35px;">8 </th> <th style="width:30px;">64 </th> <td colspan="8"><i><a href="#TTL">Time to Live</a></i> </td> <td colspan="8"><i><a href="/wiki/List_of_IP_protocol_numbers" title="List of IP protocol numbers">Protocol</a></i> </td> <td colspan="16"><i><a href="#Header_checksum">Header Checksum</a></i> </td></tr> <tr> <th style="width:35px;">12 </th> <th style="width:30px;">96 </th> <td colspan="32"><i><a href="#Source_address">Source address</a></i> </td></tr> <tr> <th style="width:35px;">16 </th> <th style="width:30px;">128 </th> <td colspan="32"><i><a href="#Destination_address">Destination address</a></i> </td></tr> <tr> <th style="width:35px;">20 </th> <th style="width:30px;">160 </th> <td colspan="32" rowspan="3" style="background: linen;"><i>(<a href="#Options">Options</a>) (if IHL > 5)</i> </td></tr> <tr> <th>⋮ </th> <th>⋮ </th></tr> <tr> <th>56 </th> <th>448 </th></tr></tbody></table> <dl><dt><style data-mw-deduplicate="TemplateStyles:r1238216509">.mw-parser-output .vanchor>:target~.vanchor-text{background-color:#b1d2ff}@media screen{html.skin-theme-clientpref-night .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}</style><span class="vanchor"><span id="Version"></span><span class="vanchor-text">Version</span></span>: 4 bits</dt> <dd>The first header field in an IP <a href="/wiki/Packet_(information_technology)" class="mw-redirect" title="Packet (information technology)">packet</a> is the <i>Version</i> field. For IPv4, this is always equal to <style data-mw-deduplicate="TemplateStyles:r886049734">.mw-parser-output .monospaced{font-family:monospace,monospace}</style><span class="monospaced">4</span>.</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Internet_Header_Length"></span><span id="IHL"></span><span class="vanchor-text">Internet Header Length</span></span><span class="nowrap"> </span>(IHL): 4 bits</dt> <dd>The IPv4 header is variable in size due to the optional 14th field (<i>Options</i>). The IHL field contains the size of the IPv4 header; it has 4 bits that specify the number of 32-bit words in the header. The minimum value for this field is 5,<sup id="cite_ref-rfc791_33-0" class="reference"><a href="#cite_note-rfc791-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> which indicates a length of 5 × 32 bits = 160 bits = 20 bytes. As a 4-bit field, the maximum value is 15; this means that the maximum size of the IPv4 header is 15 × 32 bits = 480 bits = 60 bytes.</dd> <dt><a href="/wiki/Differentiated_Services_Code_Point" class="mw-redirect" title="Differentiated Services Code Point">Differentiated Services Code Point</a><span class="nowrap"> </span>(<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="DSCP"></span><span class="vanchor-text">DSCP</span></span>): 6 bits</dt> <dd>Originally defined as the <a href="/wiki/Type_of_service" title="Type of service">type of service</a> (ToS), this field specifies <a href="/wiki/Differentiated_services" title="Differentiated services">differentiated services</a> (DiffServ).<sup id="cite_ref-rfc2474_34-0" class="reference"><a href="#cite_note-rfc2474-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> Real-time data streaming makes use of the DSCP field. An example is <a href="/wiki/Voice_over_IP" title="Voice over IP">Voice over IP</a> (VoIP), which is used for interactive voice services.</dd> <dt><a href="/wiki/Explicit_Congestion_Notification" title="Explicit Congestion Notification">Explicit Congestion Notification</a><span class="nowrap"> </span>(<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="ECN"></span><span class="vanchor-text">ECN</span></span>): 2 bits</dt> <dd>This field allows end-to-end notification of <a href="/wiki/Network_congestion" title="Network congestion">network congestion</a> without <a href="/wiki/Packet_loss" title="Packet loss">dropping packets</a>.<sup id="cite_ref-rfc3168_35-0" class="reference"><a href="#cite_note-rfc3168-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> ECN is an optional feature available when both endpoints support it and effective when also supported by the underlying network.</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Total_Length"></span><span class="vanchor-text">Total Length</span></span>: 16 bits</dt> <dd>This <a href="/wiki/16-bit" class="mw-redirect" title="16-bit">16-bit</a> field defines the entire packet size in bytes, including header and data. The minimum size is 20 bytes (header without data) and the maximum is 65,535 bytes. All hosts are required to be able to reassemble datagrams of size up to 576 bytes, but most modern hosts handle much larger packets. Links may impose further restrictions on the packet size, in which case datagrams must be <a href="/wiki/IP_fragmentation" title="IP fragmentation">fragmented</a>. Fragmentation in IPv4 is performed in either the sending host or in routers. Reassembly is performed at the receiving host.</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Identification"></span><span class="vanchor-text">Identification</span></span>: 16 bits</dt> <dd>This field is an identification field and is primarily used for uniquely identifying the group of fragments of a single IP datagram. Some experimental work has suggested using the ID field for other purposes, such as for adding packet-tracing information to help trace datagrams with spoofed source addresses,<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> but any such use is now prohibited.<sup id="cite_ref-rfc6864_37-0" class="reference"><a href="#cite_note-rfc6864-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup></dd> <dt>Flags: 3 bits</dt> <dd>There are three flags defined within this field. <dl><dt>Reserved<span class="nowrap"> </span>(R): 1 bit</dt> <dd>Reserved. Should be set to 0.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup></dd> <dt>Don't Fragment<span class="nowrap"> </span>(DF): 1 bit</dt> <dd>This field specifies whether the datagram can be fragmented or not. This can be used when sending packets to a host that does not have resources to perform reassembly of fragments. It can also be used for <a href="/wiki/Path_MTU_discovery" class="mw-redirect" title="Path MTU discovery">path MTU discovery</a>, either automatically by the host IP software, or manually using diagnostic tools such as <a href="/wiki/Ping_(networking_utility)" title="Ping (networking utility)">ping</a> or <a href="/wiki/Traceroute" title="Traceroute">traceroute</a>. If the DF flag is set, and fragmentation is required to route the packet, then the packet is dropped.</dd> <dt>More Fragments<span class="nowrap"> </span>(MF): 1 bit</dt> <dd>For unfragmented packets, the MF flag is cleared. For fragmented packets, all fragments except the last have the MF flag set. The last fragment has a non-zero <i>Fragment Offset</i> field, so it can still be differentiated from an unfragmented packet.</dd></dl></dd></dl> <dl><dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Fragment_Offset"></span><span class="vanchor-text">Fragment Offset</span></span>: 13 bits</dt> <dd>This field specifies the offset of a particular fragment relative to the beginning of the original unfragmented IP datagram. Fragments are specified in units of 8 bytes, which is why fragment lengths are always a multiple of 8; except the last, which may be smaller.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><br />The fragmentation offset value for the first fragment is always 0. The field is 13 bits wide, so the offset value ranges from 0 to 8191 (from (2<sup>0</sup> – 1) to (2<sup>13</sup> – 1)). Therefore, it allows a maximum fragment offset of (2<sup>13</sup> – 1) × 8 = 65,528 bytes, with the header length included (65,528 + 20 = 65,548 bytes), supporting fragmentation of packets exceeding the maximum IP length of 65,535 bytes.</dd> <dt>Time to live<span class="nowrap"> </span>(<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="TTL"></span><span class="vanchor-text">TTL</span></span>): 8 bits</dt> <dd>The <a href="/wiki/Time_to_live" title="Time to live">time to live</a> field limits a datagram's lifetime to prevent network failure in the event of a <a href="/wiki/Routing_loop" title="Routing loop">routing loop</a>. It is specified in seconds, but time intervals less than 1 second are rounded up to 1. In practice, the field is used as a <a href="/wiki/Hop_count" class="mw-redirect" title="Hop count">hop count</a>—when the datagram arrives at a <a href="/wiki/Router_(computing)" title="Router (computing)">router</a>, the router decrements the TTL field by one. When the TTL field hits zero, the router discards the packet and typically sends an <a href="/wiki/ICMP_time_exceeded" class="mw-redirect" title="ICMP time exceeded">ICMP time exceeded</a> message to the sender.</dd> <dd>The program <i>traceroute</i> sends messages with adjusted TTL values and uses these ICMP time exceeded messages to identify the routers traversed by packets from the source to the destination.</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Protocol"></span><span class="vanchor-text">Protocol</span></span>: 8 bits</dt> <dd>This field defines the <a href="/wiki/Transport_layer" title="Transport layer">transport layer</a> protocol used in the data portion of the IP datagram. The <a href="/wiki/List_of_IP_protocol_numbers" title="List of IP protocol numbers">list of IP protocol numbers</a> is maintained by <a href="/wiki/Internet_Assigned_Numbers_Authority" title="Internet Assigned Numbers Authority">Internet Assigned Numbers Authority</a> (IANA).<sup id="cite_ref-rfc3232_17-1" class="reference"><a href="#cite_note-rfc3232-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></dd> <dd>Some of the common payload protocols include:</dd></dl> <dl><dd><table class="wikitable"> <tbody><tr> <th>Protocol Number</th> <th>Protocol Name</th> <th>Abbreviation </th></tr> <tr> <td>1</td> <td><a href="/wiki/Internet_Control_Message_Protocol" title="Internet Control Message Protocol">Internet Control Message Protocol</a></td> <td>ICMP </td></tr> <tr> <td>2</td> <td><a href="/wiki/Internet_Group_Management_Protocol" title="Internet Group Management Protocol">Internet Group Management Protocol</a></td> <td>IGMP </td></tr> <tr> <td>6</td> <td><a href="/wiki/Transmission_Control_Protocol" title="Transmission Control Protocol">Transmission Control Protocol</a></td> <td>TCP </td></tr> <tr> <td>17</td> <td><a href="/wiki/User_Datagram_Protocol" title="User Datagram Protocol">User Datagram Protocol</a></td> <td>UDP </td></tr> <tr> <td>41</td> <td><a href="/wiki/IPv6#Tunneling" title="IPv6">IPv6 encapsulation</a></td> <td>ENCAP </td></tr> <tr> <td>89</td> <td><a href="/wiki/Open_Shortest_Path_First" title="Open Shortest Path First">Open Shortest Path First</a></td> <td>OSPF </td></tr> <tr> <td>132</td> <td><a href="/wiki/Stream_Control_Transmission_Protocol" title="Stream Control Transmission Protocol">Stream Control Transmission Protocol</a></td> <td>SCTP </td></tr></tbody></table></dd></dl> <dl><dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Header_Checksum"></span><span class="vanchor-text">Header Checksum</span></span>: 16 bits</dt> <dd>The <a href="/wiki/IPv4_header_checksum" class="mw-redirect" title="IPv4 header checksum">IPv4 header checksum</a> field is used for error checking of the header. Before sending a packet, the checksum is computed as the 16-bit <a href="/wiki/Ones%27_complement" title="Ones' complement">ones' complement</a> of the ones' complement sum of all 16-bit words in the header. This includes the <i>Header Checksum</i> field itself, which is set to zero during computation. The packet is sent with <i>Header Checksum</i> containing the resulting value. When a packet arrives at a router or its destination, the network device recalculates the checksum value of the header, now including the <i>Header Checksum</i> field. The result should be zero; if a different result is obtained, the device discards the packet.</dd> <dd>When a packet arrives at a router, the router decreases the <i>TTL</i> field in the header. Consequently, the router must calculate a new header checksum before sending it out again.</dd> <dd>Errors in the data portion of the packet are handled separately by the encapsulated protocol. Both <a href="/wiki/User_Datagram_Protocol" title="User Datagram Protocol">UDP</a> and <a href="/wiki/Transmission_Control_Protocol" title="Transmission Control Protocol">TCP</a> have separate checksums that apply to their data.</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Source_address"></span><span class="vanchor-text">Source address</span></span>: 32 bits</dt> <dd>This field contains the <a href="/wiki/IPv4_address" class="mw-redirect" title="IPv4 address">IPv4 address</a> of the sender of the packet. It may be changed in transit by <a href="/wiki/Network_address_translation" title="Network address translation">network address translation</a> (NAT).</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Destination_address"></span><span class="vanchor-text">Destination address</span></span>: 32 bits</dt> <dd>This field contains the <a href="/wiki/IPv4_address" class="mw-redirect" title="IPv4 address">IPv4 address</a> of the intended receiver of the packet. It may also be affected by NAT.</dd> <dd>If the destination can be <a href="/wiki/Broadcast_domain" title="Broadcast domain">reached directly</a> the packet will be delivered by the underlying <a href="/wiki/Link_layer" title="Link layer">link layer</a>, with the help of <a href="/wiki/Address_Resolution_Protocol" title="Address Resolution Protocol">ARP</a>. If not, the packet needs <a href="/wiki/Routing" title="Routing">routing</a> and will be delivered to <a href="/wiki/Gateway_address" title="Gateway address">gateway address</a> instead.</dd> <dt><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238216509"><span class="vanchor"><span id="Options"></span><span class="vanchor-text">Options</span></span>: 0 - 320 bits, padded to multiples of 32 bits</dt> <dd>The <i>Options</i> field is not often used. Packets containing <a href="/wiki/Internet_Protocol_Options_Considerations" class="mw-redirect" title="Internet Protocol Options Considerations">some options may be considered as dangerous</a> by some routers and be blocked.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> The value in the <i>IHL</i> field must include sufficient extra 32-bit words to hold all options and any padding needed to ensure that the header contains an integral number of 32-bit words. If <i>IHL</i> is greater than 5 (i.e., it is from 6 to 15) it means that the options field is present and must be considered. The list of options may be terminated with the option EOOL (End of Options List, 0x00); this is only necessary if the end of the options would not otherwise coincide with the end of the header.</dd> <dd>Since most of the IP options include specifications on how many or which intermediate devices the packet should pass, the IP options are not used for communication over the Internet and IP packets including some of the IP options must be dropped,<sup id="cite_ref-rfc6274_42-0" class="reference"><a href="#cite_note-rfc6274-42"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Location: §3.13">: §3.13 </span></sup> since they can expose the network topology or network details.</dd></dl> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Internet_Protocol_Options" title="Internet Protocol Options">Internet Protocol Options</a></div> <div class="mw-heading mw-heading2"><h2 id="Fragmentation_and_reassembly">Fragmentation and reassembly</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=16" title="Edit section: Fragmentation and reassembly"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/IP_fragmentation" title="IP fragmentation">IP fragmentation</a></div> <p>The Internet Protocol enables traffic between networks. The design accommodates networks of diverse physical nature; it is independent of the underlying transmission technology used in the link layer. Networks with different hardware usually vary not only in transmission speed, but also in the <a href="/wiki/Maximum_transmission_unit" title="Maximum transmission unit">maximum transmission unit</a> (MTU). When one network wants to transmit datagrams to a network with a smaller MTU, it may <a href="/wiki/IP_fragmentation" title="IP fragmentation">fragment</a> its datagrams. In IPv4, this function was placed at the <a href="/wiki/Internet_Layer" class="mw-redirect" title="Internet Layer">Internet Layer</a> and is performed in IPv4 routers limiting exposure to these issues by hosts. </p><p>In contrast, <a href="/wiki/IPv6" title="IPv6">IPv6</a>, the next generation of the Internet Protocol, does not allow routers to perform fragmentation; hosts must perform <a href="/wiki/Path_MTU_Discovery" title="Path MTU Discovery">Path MTU Discovery</a> before sending datagrams. </p> <div class="mw-heading mw-heading3"><h3 id="Fragmentation">Fragmentation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=17" title="Edit section: Fragmentation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>When a router receives a packet, it examines the destination address and determines the outgoing interface to use and that interface's MTU. If the packet size is bigger than the MTU, and the Do not Fragment (DF) bit in the packet's header is set to 0, then the router may fragment the packet. </p><p>The router divides the packet into fragments. The maximum size of each fragment is the outgoing MTU minus the IP header size (20 bytes minimum; 60 bytes maximum). The router puts each fragment into its own packet, each fragment packet having the following changes: </p> <ul><li>The <i>total length</i> field is the fragment size.</li> <li>The <i>more fragments</i> (MF) flag is set for all fragments except the last one, which is set to 0.</li> <li>The <i>fragment offset</i> field is set, based on the offset of the fragment in the original data payload. This is measured in units of 8-byte blocks.</li> <li>The <i>header checksum</i> field is recomputed.</li></ul> <p>For example, for an MTU of 1,500 bytes and a header size of 20 bytes, the fragment offsets would be multiples of <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {1{,}500-20}{8}}=185}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>1,500</mn> <mo>−</mo> <mn>20</mn> </mrow> <mn>8</mn> </mfrac> </mrow> <mo>=</mo> <mn>185</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {1{,}500-20}{8}}=185}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/83427d12010e706454db8d36b294c51309896e38" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:17.884ex; height:5.343ex;" alt="{\displaystyle {\frac {1{,}500-20}{8}}=185}"></span> (0, 185, 370, 555, 740, etc.). </p><p>It is possible that a packet is fragmented at one router, and that the fragments are further fragmented at another router. For example, a packet of 4,520 bytes, including a 20 bytes IP header is fragmented to two packets on a link with an MTU of 2,500 bytes: </p> <table class="wikitable" style="text-align:center"> <tbody><tr> <th>Fragment </th> <th>Size<br /><small>(bytes)</small> </th> <th>Header size<br /><small>(bytes)</small> </th> <th>Data size<br /><small>(bytes)</small> </th> <th>Flag<br /><i>More fragments</i> </th> <th>Fragment offset<br /><small>(8-byte blocks)</small> </th></tr> <tr> <td>1 </td> <td>2,500 </td> <td>20 </td> <td>2,480 </td> <td>1 </td> <td>0 </td></tr> <tr> <td>2 </td> <td>2,040 </td> <td>20 </td> <td>2,020 </td> <td>0 </td> <td>310 </td></tr></tbody></table> <p>The total data size is preserved: 2,480 bytes + 2,020 bytes = 4,500 bytes. The offsets are <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 0}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>0</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 0}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2aae8864a3c1fec9585261791a809ddec1489950" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.162ex; height:2.176ex;" alt="{\displaystyle 0}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\frac {0+2{,}480}{8}}=310}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mn>0</mn> <mo>+</mo> <mn>2,480</mn> </mrow> <mn>8</mn> </mfrac> </mrow> <mo>=</mo> <mn>310</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\frac {0+2{,}480}{8}}=310}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d9b250ee44d588aae433baeaf51bf53027e54d4b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:16.721ex; height:5.343ex;" alt="{\displaystyle {\frac {0+2{,}480}{8}}=310}"></span>. </p><p>When forwarded to a link with an MTU of 1,500 bytes, each fragment is fragmented into two fragments: </p> <table class="wikitable" style="text-align:center"> <tbody><tr> <th>Fragment </th> <th>Size<br /><small>(bytes)</small> </th> <th>Header size<br /><small>(bytes)</small> </th> <th>Data size<br /><small>(bytes)</small> </th> <th>Flag<br /><i>More fragments</i> </th> <th>Fragment offset<br /><small>(8-byte blocks)</small> </th></tr> <tr> <td>1 </td> <td>1,500 </td> <td>20 </td> <td>1,480 </td> <td>1 </td> <td>0 </td></tr> <tr> <td>2 </td> <td>1,020 </td> <td>20 </td> <td>1,000 </td> <td>1 </td> <td>185 </td></tr> <tr> <td>3 </td> <td>1,500 </td> <td>20 </td> <td>1,480 </td> <td>1 </td> <td>310 </td></tr> <tr> <td>4 </td> <td>560 </td> <td>20 </td> <td>540 </td> <td>0 </td> <td>495 </td></tr></tbody></table> <p>Again, the data size is preserved: 1,480 + 1,000 = 2,480, and 1,480 + 540 = 2,020. </p><p>Also in this case, the <i>More Fragments</i> bit remains 1 for all the fragments that came with 1 in them and for the last fragment that arrives, it works as usual, that is the MF bit is set to 0 only in the last one. And of course, the Identification field continues to have the same value in all re-fragmented fragments. This way, even if fragments are re-fragmented, the receiver knows they have initially all started from the same packet. </p><p>The last offset and last data size are used to calculate the total data size: <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 495\times 8+540=3{,}960+540=4{,}500}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>495</mn> <mo>×</mo> <mn>8</mn> <mo>+</mo> <mn>540</mn> <mo>=</mo> <mn>3,960</mn> <mo>+</mo> <mn>540</mn> <mo>=</mo> <mn>4,500</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 495\times 8+540=3{,}960+540=4{,}500}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/519a8b86dfb7595692e093326021d89fcd054ef5" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:36.936ex; height:2.509ex;" alt="{\displaystyle 495\times 8+540=3{,}960+540=4{,}500}"></span>. </p> <div class="mw-heading mw-heading3"><h3 id="Reassembly">Reassembly</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=18" title="Edit section: Reassembly"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A receiver knows that a packet is a fragment, if at least one of the following conditions is true: </p> <ul><li>The flag <i>more fragments</i> is set, which is true for all fragments except the last.</li> <li>The field <i>fragment offset</i> is nonzero, which is true for all fragments except the first.</li></ul> <p>The receiver identifies matching fragments using the source and destination addresses, the protocol ID, and the identification field. The receiver reassembles the data from fragments with the same ID using both the fragment offset and the more fragments flag. When the receiver receives the last fragment, which has the <i>more fragments</i> flag set to 0, it can calculate the size of the original data payload, by multiplying the last fragment's offset by eight and adding the last fragment's data size. In the given example, this calculation was <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 495\times 8+540=4{,}500}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>495</mn> <mo>×</mo> <mn>8</mn> <mo>+</mo> <mn>540</mn> <mo>=</mo> <mn>4,500</mn> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 495\times 8+540=4{,}500}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/6b6a90ff9b64823f2b2e69716639e40b6e7f4870" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:22.213ex; height:2.509ex;" alt="{\displaystyle 495\times 8+540=4{,}500}"></span> bytes. When the receiver has all fragments, they can be reassembled in the correct sequence according to the offsets to form the original datagram. </p> <div class="mw-heading mw-heading2"><h2 id="Assistive_protocols">Assistive protocols</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=19" title="Edit section: Assistive protocols"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>IP addresses are not tied in any permanent manner to networking hardware and, indeed, in modern <a href="/wiki/Operating_system" title="Operating system">operating systems</a>, a network interface can have multiple IP addresses. In order to properly deliver an IP packet to the destination host on a link, hosts and routers need additional mechanisms to make an association between the hardware address<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>b<span class="cite-bracket">]</span></a></sup> of network interfaces and IP addresses. The <a href="/wiki/Address_Resolution_Protocol" title="Address Resolution Protocol">Address Resolution Protocol</a> (ARP) performs this IP-address-to-hardware-address translation for IPv4. In addition, the reverse correlation is often necessary. For example, unless an address is preconfigured by an administrator, when an IP host is booted or connected to a network it needs to determine its IP address. Protocols for such reverse correlations include <a href="/wiki/Dynamic_Host_Configuration_Protocol" title="Dynamic Host Configuration Protocol">Dynamic Host Configuration Protocol</a> (DHCP), <a href="/wiki/Bootstrap_Protocol" title="Bootstrap Protocol">Bootstrap Protocol</a> (BOOTP) and, infrequently, <a href="/wiki/Reverse_ARP" class="mw-redirect" title="Reverse ARP">reverse ARP</a>. </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=20" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/History_of_the_Internet" title="History of the Internet">History of the Internet</a></li> <li><a href="/wiki/List_of_assigned_/8_IPv4_address_blocks" title="List of assigned /8 IPv4 address blocks">List of assigned /8 IPv4 address blocks</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=21" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text">As an <a href="/wiki/April_Fools%27" class="mw-redirect" title="April Fools'">April Fools'</a> joke, proposed for use in RFC 3514 as the "<a href="/wiki/Evil_bit" title="Evil bit">Evil bit</a>"<sup id="cite_ref-rfc3514_38-0" class="reference"><a href="#cite_note-rfc3514-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup></span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text">For <a href="/wiki/IEEE_802" title="IEEE 802">IEEE 802</a> networking technologies, including <a href="/wiki/Ethernet" title="Ethernet">Ethernet</a>, the hardware address is a <a href="/wiki/MAC_address" title="MAC address">MAC address</a>.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=22" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><span typeof="mw:File"><a href="/wiki/File:Open_Access_logo_PLoS_transparent.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/77/Open_Access_logo_PLoS_transparent.svg/9px-Open_Access_logo_PLoS_transparent.svg.png" decoding="async" width="9" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/77/Open_Access_logo_PLoS_transparent.svg/14px-Open_Access_logo_PLoS_transparent.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/77/Open_Access_logo_PLoS_transparent.svg/18px-Open_Access_logo_PLoS_transparent.svg.png 2x" data-file-width="640" data-file-height="1000" /></a></span> <span class="plainlinks">This article was adapted from the following source under a <span class="plainlinks"><a rel="nofollow" class="external text" href="https://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a></span> license (<a class="external text" href="https://en.wikipedia.org/w/index.php?title=IPv4&action=history&date-range-to=2022-12-11">2022</a>) : <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation journal cs1">Michel Bakni; Sandra Hanbo (9 December 2022). <a class="external text" href="https://upload.wikimedia.org/wikiversity/en/d/db/A_Survey_on_Internet_Protocol_version_4_%28IPv4%29.pdf">"A Survey on Internet Protocol version 4 (IPv4)"</a> <span class="cs1-format">(PDF)</span>. <i>WikiJournal of Science</i>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.15347%2FWJS%2F2022.002">10.15347/WJS/2022.002</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2470-6345">2470-6345</a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/9708517136">9708517136</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:254665961">254665961</a>. <a href="/wiki/WDQ_(identifier)" class="mw-redirect" title="WDQ (identifier)">Wikidata</a> <a href="https://www.wikidata.org/wiki/Q104661268" class="extiw" title="d:Q104661268">Q104661268</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=WikiJournal+of+Science&rft.atitle=A+Survey+on+Internet+Protocol+version+4+%28IPv4%29&rft.date=2022-12-09&rft_id=info%3Aoclcnum%2F9708517136&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A254665961%23id-name%3DS2CID&rft.issn=2470-6345&rft_id=info%3Adoi%2F10.15347%2FWJS%2F2022.002&rft.au=Michel+Bakni&rft.au=Sandra+Hanbo&rft_id=https%3A%2F%2Fupload.wikimedia.org%2Fwikiversity%2Fen%2Fd%2Fdb%2FA_Survey_on_Internet_Protocol_version_4_%2528IPv4%2529.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </p> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-:0-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-:0_1-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://bgp.potaroo.net/index-bgp.html">"BGP Analysis Reports"</a>. <i>BGP Reports</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2013-01-09</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=BGP+Reports&rft.atitle=BGP+Analysis+Reports&rft_id=http%3A%2F%2Fbgp.potaroo.net%2Findex-bgp.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.google.com/intl/en/ipv6/statistics.html">"IPv6 – Google"</a>. <i>www.google.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-01-28</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.google.com&rft.atitle=IPv6+%E2%80%93+Google&rft_id=https%3A%2F%2Fwww.google.com%2Fintl%2Fen%2Fipv6%2Fstatistics.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml">"IANA IPv4 Special-Purpose Address Registry"</a>. <i>www.iana.org</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-01-28</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.iana.org&rft.atitle=IANA+IPv4+Special-Purpose+Address+Registry&rft_id=https%3A%2F%2Fwww.iana.org%2Fassignments%2Fiana-ipv4-special-registry%2Fiana-ipv4-special-registry.xhtml&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc6890-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-rfc6890_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-rfc6890_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-rfc6890_4-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-rfc6890_4-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-rfc6890_4-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-rfc6890_4-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFM._CottonL._VegodaB._Haberman2013" class="citation cs1">M. Cotton; L. Vegoda; B. Haberman (April 2013). R. Bonica (ed.). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6890"><i>Special-Purpose IP Address Registries</i></a>. <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC6890">10.17487/RFC6890</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. BCP 153. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6890">6890</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Special-Purpose+IP+Address+Registries&rft.pub=IETF&rft.date=2013-04&rft_id=info%3Adoi%2F10.17487%2FRFC6890&rft.issn=2070-1721&rft.au=M.+Cotton&rft.au=L.+Vegoda&rft.au=B.+Haberman&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc6890&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Best Current Practice 153.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc4773">4773</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5156">5156</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5735">5735</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5736">5736</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8190">8190</a>. </span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDavis" class="citation web cs1">Davis, Lidija. <a rel="nofollow" class="external text" href="https://archive.nytimes.com/www.nytimes.com/external/readwriteweb/2009/02/21/21readwriteweb-vint_cerf_we_still_have_80_per.html">"Vint Cerf - We Still Have 80 Per Cent of the World to Connect"</a>. <i><a href="/wiki/The_New_York_Times" title="The New York Times">The New York Times</a></i><span class="reference-accessdate">. Retrieved <span class="nowrap">2024-05-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+New+York+Times&rft.atitle=Vint+Cerf+-+We+Still+Have+80+Per+Cent+of+the+World+to+Connect&rft.aulast=Davis&rft.aufirst=Lidija&rft_id=https%3A%2F%2Farchive.nytimes.com%2Fwww.nytimes.com%2Fexternal%2Freadwriteweb%2F2009%2F02%2F21%2F21readwriteweb-vint_cerf_we_still_have_80_per.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://ipv4marketgroup.com/a-brief-history-of-ipv4/">"A Brief History of IPv4"</a>. <i>IPv4 Market Group</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2020-08-19</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=IPv4+Market+Group&rft.atitle=A+Brief+History+of+IPv4&rft_id=https%3A%2F%2Fipv4marketgroup.com%2Fa-brief-history-of-ipv4%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20010616012053/http://www.3com.com/other/pdfs/infra/corpinfo/en_US/501302.pdf">"Understanding IP Addressing: Everything You Ever Wanted To Know"</a> <span class="cs1-format">(PDF)</span>. 3Com. Archived from <a rel="nofollow" class="external text" href="http://www.3com.com/other/pdfs/infra/corpinfo/en_US/501302.pdf">the original</a> <span class="cs1-format">(PDF)</span> on June 16, 2001.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Understanding+IP+Addressing%3A+Everything+You+Ever+Wanted+To+Know&rft.pub=3Com&rft_id=http%3A%2F%2Fwww.3com.com%2Fother%2Fpdfs%2Finfra%2Fcorpinfo%2Fen_US%2F501302.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc1918-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-rfc1918_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-rfc1918_8-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-rfc1918_8-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-rfc1918_8-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFY._RekhterB._MoskowitzD._KarrenbergG._J._de_Groot1996" class="citation cs1"><a href="/wiki/Yakov_Rekhter" title="Yakov Rekhter">Y. Rekhter</a>; B. Moskowitz; D. Karrenberg; G. J. de Groot; E. Lear (February 1996). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1918"><i>Address Allocation for Private Internets</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC1918">10.17487/RFC1918</a></span>. BCP 5. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1918">1918</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Address+Allocation+for+Private+Internets&rft.pub=Network+Working+Group&rft.date=1996-02&rft_id=info%3Adoi%2F10.17487%2FRFC1918&rft.au=Y.+Rekhter&rft.au=B.+Moskowitz&rft.au=D.+Karrenberg&rft.au=G.+J.+de+Groot&rft.au=E.+Lear&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc1918&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Best Current Practice 5.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1627">1627</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1597">1597</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6761">6761</a>. </span> </li> <li id="cite_note-rfc6598-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc6598_9-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJ._WeilV._KuarsinghC._DonleyC._Liljenstolpe2012" class="citation cs1">J. Weil; V. Kuarsingh; C. Donley; C. Liljenstolpe; M. Azinger (April 2012). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6598"><i>IANA-Reserved IPv4 Prefix for Shared Address Space</i></a>. <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC6598">10.17487/RFC6598</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. BCP 153. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6598">6598</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IANA-Reserved+IPv4+Prefix+for+Shared+Address+Space&rft.pub=Internet+Engineering+Task+Force&rft.date=2012-04&rft_id=info%3Adoi%2F10.17487%2FRFC6598&rft.issn=2070-1721&rft.au=J.+Weil&rft.au=V.+Kuarsingh&rft.au=C.+Donley&rft.au=C.+Liljenstolpe&rft.au=M.+Azinger&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc6598&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Best Common Practice.</i> Updates <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5735">5735</a>. </span> </li> <li id="cite_note-rfc3927-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc3927_10-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFS._CheshireB._AbobaE._Guttman2005" class="citation cs1"><a href="/wiki/Stuart_Cheshire" title="Stuart Cheshire">S. Cheshire</a>; B. Aboba; E. Guttman (May 2005). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3927"><i>Dynamic Configuration of IPv4 Link-Local Addresses</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3927">10.17487/RFC3927</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3927">3927</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Dynamic+Configuration+of+IPv4+Link-Local+Addresses&rft.pub=Network+Working+Group&rft.date=2005-05&rft_id=info%3Adoi%2F10.17487%2FRFC3927&rft.au=S.+Cheshire&rft.au=B.+Aboba&rft.au=E.+Guttman&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3927&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> </span> </li> <li id="cite_note-rfc5737-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-rfc5737_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-rfc5737_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-rfc5737_11-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJ._ArkkoM._CottonL._Vegoda2010" class="citation cs1">J. Arkko; M. Cotton; L. Vegoda (January 2010). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5737"><i>IPv4 Address Blocks Reserved for Documentation</i></a>. <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC5737">10.17487/RFC5737</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5737">5737</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IPv4+Address+Blocks+Reserved+for+Documentation&rft.pub=Internet+Engineering+Task+Force&rft.date=2010-01&rft_id=info%3Adoi%2F10.17487%2FRFC5737&rft.issn=2070-1721&rft.au=J.+Arkko&rft.au=M.+Cotton&rft.au=L.+Vegoda&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc5737&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> Updates <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1166">1166</a>. </span> </li> <li id="cite_note-rfc7526-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc7526_12-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFO._Troan2015" class="citation cs1">O. Troan (May 2015). <a href="/wiki/Brian_Carpenter_(engineer)" title="Brian Carpenter (engineer)">B. Carpenter</a> (ed.). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7526"><i>Deprecating the Anycast Prefix for 6to4 Relay Routers</i></a>. <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC7526">10.17487/RFC7526</a></span>. BCP 196. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7526">7526</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Deprecating+the+Anycast+Prefix+for+6to4+Relay+Routers&rft.pub=Internet+Engineering+Task+Force&rft.date=2015-05&rft_id=info%3Adoi%2F10.17487%2FRFC7526&rft.au=O.+Troan&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc7526&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Best Current Practice.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3068">3068</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6732">6732</a>. </span> </li> <li id="cite_note-rfc3068-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc3068_13-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFC._Huitema2001" class="citation cs1"><a href="/wiki/Christian_Huitema" title="Christian Huitema">C. Huitema</a> (June 2001). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3068"><i>An Anycast Prefix for 6to4 Relay Routers</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3068">10.17487/RFC3068</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3068">3068</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=An+Anycast+Prefix+for+6to4+Relay+Routers&rft.pub=Network+Working+Group&rft.date=2001-06&rft_id=info%3Adoi%2F10.17487%2FRFC3068&rft.au=C.+Huitema&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3068&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> Obsoleted by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7526">7526</a>. </span> </li> <li id="cite_note-rfc2544-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc2544_14-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFS._BradnerJ._McQuaid1999" class="citation cs1">S. Bradner; J. McQuaid (March 1999). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2544"><i>Benchmarking Methodology for Network Interconnect Devices</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC2544">10.17487/RFC2544</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2544">2544</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Benchmarking+Methodology+for+Network+Interconnect+Devices&rft.pub=Network+Working+Group&rft.date=1999-03&rft_id=info%3Adoi%2F10.17487%2FRFC2544&rft.au=S.+Bradner&rft.au=J.+McQuaid&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc2544&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> Updated by: <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6201">6201</a> and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6815">6815</a>. </span> </li> <li id="cite_note-rfc5771-15"><span class="mw-cite-backlink">^ <a href="#cite_ref-rfc5771_15-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-rfc5771_15-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFM._CottonL._VegodaD._Meyer2010" class="citation cs1">M. Cotton; L. Vegoda; D. Meyer (March 2010). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5771"><i>IANA Guidelines for IPv4 Multicast Address Assignments</i></a>. <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC5771">10.17487/RFC5771</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. BCP 51. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5771">5771</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IANA+Guidelines+for+IPv4+Multicast+Address+Assignments&rft.pub=IETF&rft.date=2010-03&rft_id=info%3Adoi%2F10.17487%2FRFC5771&rft.issn=2070-1721&rft.au=M.+Cotton&rft.au=L.+Vegoda&rft.au=D.+Meyer&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc5771&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Best Current Practice 51.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3138">3138</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3171">3171</a>. Updates <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2780">2780</a>. </span> </li> <li id="cite_note-rfc6676-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc6676_16-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFS._VenaasR._ParekhG._Van_de_VeldeT._Chown2012" class="citation cs1">S. Venaas; R. Parekh; G. Van de Velde; T. Chown; M. Eubanks (August 2012). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6676"><i>Multicast Addresses for Documentation</i></a>. <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC6676">10.17487/RFC6676</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6676">6676</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Multicast+Addresses+for+Documentation&rft.pub=Internet+Engineering+Task+Force&rft.date=2012-08&rft_id=info%3Adoi%2F10.17487%2FRFC6676&rft.issn=2070-1721&rft.au=S.+Venaas&rft.au=R.+Parekh&rft.au=G.+Van+de+Velde&rft.au=T.+Chown&rft.au=M.+Eubanks&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc6676&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> </span> </li> <li id="cite_note-rfc3232-17"><span class="mw-cite-backlink">^ <a href="#cite_ref-rfc3232_17-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-rfc3232_17-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJ._Reynolds2002" class="citation cs1"><a href="/wiki/Joyce_K._Reynolds" title="Joyce K. Reynolds">J. Reynolds</a>, ed. (January 2002). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3232"><i>Assigned Numbers: RFC 1700 is Replaced by an On-line Database</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3232">10.17487/RFC3232</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3232">3232</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Assigned+Numbers%3A+RFC+1700+is+Replaced+by+an+On-line+Database&rft.pub=Network+Working+Group&rft.date=2002-01&rft_id=info%3Adoi%2F10.17487%2FRFC3232&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3232&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1700">1700</a>. </span> </li> <li id="cite_note-5-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-5_18-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJ._ReynoldsJ._Postel1984" class="citation cs1"><a href="/wiki/Joyce_K._Reynolds" title="Joyce K. Reynolds">J. Reynolds</a>; <a href="/wiki/Jon_Postel" title="Jon Postel">J. Postel</a> (October 1984). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc923"><i>ASSIGNED NUMBERS</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC0923">10.17487/RFC0923</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc923">923</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=ASSIGNED+NUMBERS&rft.pub=Network+Working+Group&rft.date=1984-10&rft_id=info%3Adoi%2F10.17487%2FRFC0923&rft.au=J.+Reynolds&rft.au=J.+Postel&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc923&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Obsolete.</i> Obsoleted by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc943">943</a>. Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc900">900</a>. <q>Special Addresses: In certain contexts, it is useful to have fixed addresses with functional significance rather than as identifiers of specific hosts. When such usage is called for, the address zero is to be interpreted as meaning "this", as in "this network".</q> </span> </li> <li id="cite_note-rfc1122-19"><span class="mw-cite-backlink">^ <a href="#cite_ref-rfc1122_19-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-rfc1122_19-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFR._Braden1989" class="citation cs1"><a href="/wiki/Bob_Braden" title="Bob Braden">R. Braden</a>, ed. (October 1989). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1122"><i>Requirements for Internet Hosts -- Communication Layers</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC1122">10.17487/RFC1122</a></span>. STD 3. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1122">1122</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Requirements+for+Internet+Hosts+--+Communication+Layers&rft.pub=Network+Working+Group&rft.date=1989-10&rft_id=info%3Adoi%2F10.17487%2FRFC1122&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc1122&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Internet Standard 3.</i> Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1349">1349</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc4379">4379</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5884">5884</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6093">6093</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6298">6298</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6633">6633</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6864">6864</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8029">8029</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9293">9293</a>. </span> </li> <li id="cite_note-rfc3021-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc3021_20-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFA._RetanaR._WhiteV._FullerD._McPherson2000" class="citation cs1">A. Retana; R. White; V. Fuller; D. McPherson (December 2000). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3021"><i>Using 31-Bit Prefixes on IPv4 Point-to-Point Links</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3021">10.17487/RFC3021</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3021">3021</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Using+31-Bit+Prefixes+on+IPv4+Point-to-Point+Links&rft.pub=Network+Working+Group&rft.date=2000-12&rft_id=info%3Adoi%2F10.17487%2FRFC3021&rft.au=A.+Retana&rft.au=R.+White&rft.au=V.+Fuller&rft.au=D.+McPherson&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3021&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> </span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAlmquistKastenholz1993" class="citation journal cs1">Almquist, Philip; Kastenholz, Frank (December 1993). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/draft-ietf-rreq-iprouters-require/00">"Towards Requirements for IP Routers"</a>. <i>Internet Engineering Task Force</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Internet+Engineering+Task+Force&rft.atitle=Towards+Requirements+for+IP+Routers&rft.date=1993-12&rft.aulast=Almquist&rft.aufirst=Philip&rft.au=Kastenholz%2C+Frank&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-rreq-iprouters-require%2F00&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc1716-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc1716_22-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFP._Almquist1994" class="citation cs1">P. Almquist (November 1994). F. Kastenholz (ed.). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1716"><i>Towards Requirements for IP Routers</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC1716">10.17487/RFC1716</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1716">1716</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Towards+Requirements+for+IP+Routers&rft.pub=Network+Working+Group&rft.date=1994-11&rft_id=info%3Adoi%2F10.17487%2FRFC1716&rft.au=P.+Almquist&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc1716&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Obsolete.</i> Obsoleted by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1812">1812</a>. </span> </li> <li id="cite_note-rfc1812-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc1812_23-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFF._Baker1995" class="citation cs1"><a href="/wiki/Fred_Baker_(IETF_chair)" class="mw-redirect" title="Fred Baker (IETF chair)">F. Baker</a>, ed. (June 1995). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1812"><i>Requirements for IP Version 4 Routers</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC1812">10.17487/RFC1812</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1812">1812</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Requirements+for+IP+Version+4+Routers&rft.pub=Network+Working+Group&rft.date=1995-06&rft_id=info%3Adoi%2F10.17487%2FRFC1812&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc1812&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1716">1716</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1009">1009</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2644">2644</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6633">6633</a>. </span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/13786-20.html">"Understanding and Configuring the ip unnumbered Command"</a>. <i>Cisco</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2021-11-25</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Cisco&rft.atitle=Understanding+and+Configuring+the+ip+unnumbered+Command&rft_id=https%3A%2F%2Fwww.cisco.com%2Fc%2Fen%2Fus%2Fsupport%2Fdocs%2Fip%2Fhot-standby-router-protocol-hsrp%2F13786-20.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110125195711/http://technology.inquirer.net/infotech/infotech/view/20110121-315808/World-running-out-of-Internet-addresses">"World 'running out of Internet addresses'<span class="cs1-kern-right"></span>"</a>. Archived from <a rel="nofollow" class="external text" href="http://technology.inquirer.net/infotech/infotech/view/20110121-315808/World-running-out-of-Internet-addresses">the original</a> on 2011-01-25<span class="reference-accessdate">. Retrieved <span class="nowrap">2011-01-23</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=World+%27running+out+of+Internet+addresses%27&rft_id=http%3A%2F%2Ftechnology.inquirer.net%2Finfotech%2Finfotech%2Fview%2F20110121-315808%2FWorld-running-out-of-Internet-addresses&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSmithLipner,_Ian2011" class="citation web cs1">Smith, Lucie; Lipner, Ian (3 February 2011). <a rel="nofollow" class="external text" href="http://www.nro.net/news/ipv4-free-pool-depleted">"Free Pool of IPv4 Address Space Depleted"</a>. <a href="/wiki/Number_Resource_Organization" class="mw-redirect" title="Number Resource Organization">Number Resource Organization</a><span class="reference-accessdate">. Retrieved <span class="nowrap">3 February</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Free+Pool+of+IPv4+Address+Space+Depleted&rft.pub=Number+Resource+Organization&rft.date=2011-02-03&rft.aulast=Smith&rft.aufirst=Lucie&rft.au=Lipner%2C+Ian&rft_id=http%3A%2F%2Fwww.nro.net%2Fnews%2Fipv4-free-pool-depleted&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFICANN,_nanog_mailing_list" class="citation web cs1">ICANN, nanog mailing list. <a rel="nofollow" class="external text" href="http://mailman.nanog.org/pipermail/nanog/2011-February/032107.html">"Five /8s allocated to RIRs – no unallocated IPv4 unicast /8s remain"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Five+%2F8s+allocated+to+RIRs+%E2%80%93+no+unallocated+IPv4+unicast+%2F8s+remain&rft.au=ICANN%2C+nanog+mailing+list&rft_id=http%3A%2F%2Fmailman.nanog.org%2Fpipermail%2Fnanog%2F2011-February%2F032107.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAsia-Pacific_Network_Information_Centre2011" class="citation web cs1">Asia-Pacific Network Information Centre (15 April 2011). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110807162057/http://www.apnic.net/publications/news/2011/final-8">"APNIC IPv4 Address Pool Reaches Final /8"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.apnic.net/publications/news/2011/final-8">the original</a> on 7 August 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">15 April</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=APNIC+IPv4+Address+Pool+Reaches+Final+%2F8&rft.date=2011-04-15&rft.au=Asia-Pacific+Network+Information+Centre&rft_id=http%3A%2F%2Fwww.apnic.net%2Fpublications%2Fnews%2F2011%2Ffinal-8&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc2460-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc2460_29-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFS._DeeringR._Hinden1998" class="citation cs1"><a href="/wiki/Steve_Deering" title="Steve Deering">S. Deering</a>; R. Hinden (December 1998). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2460"><i>Internet Protocol, Version 6 (IPv6) Specification</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC2460">10.17487/RFC2460</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2460">2460</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Internet+Protocol%2C+Version+6+%28IPv6%29+Specification&rft.pub=Network+Working+Group&rft.date=1998-12&rft_id=info%3Adoi%2F10.17487%2FRFC2460&rft.au=S.+Deering&rft.au=R.+Hinden&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc2460&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Obsolete.</i> Obsoleted by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8200">8200</a>. Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1883">1883</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5095">5095</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5722">5722</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5871">5871</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6437">6437</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6564">6564</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6935">6935</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6946">6946</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7045">7045</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7112">7112</a>. </span> </li> <li id="cite_note-rfc3701-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc3701_30-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFR._FinkR._Hinden2004" class="citation cs1">R. Fink; R. Hinden (March 2004). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3701"><i>6bone (IPv6 Testing Address Allocation) Phaseout</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3701">10.17487/RFC3701</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3701">3701</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=6bone+%28IPv6+Testing+Address+Allocation%29+Phaseout&rft.pub=Network+Working+Group&rft.date=2004-03&rft_id=info%3Adoi%2F10.17487%2FRFC3701&rft.au=R.+Fink&rft.au=R.+Hinden&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3701&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2471">2471</a>. </span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><i>2016 IEEE International Conference on Emerging Technologies and Innovative Business Practices for the Transformation of Societies (EmergiTech)</i>. Piscataway, NJ: University of Technology, Mauritius, Institute of Electrical and Electronics Engineers. August 2016. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781509007066" title="Special:BookSources/9781509007066"><bdi>9781509007066</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/972636788">972636788</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=2016+IEEE+International+Conference+on+Emerging+Technologies+and+Innovative+Business+Practices+for+the+Transformation+of+Societies+%28EmergiTech%29&rft.place=Piscataway%2C+NJ&rft.pub=University+of+Technology%2C+Mauritius%2C+Institute+of+Electrical+and+Electronics+Engineers&rft.date=2016-08&rft_id=info%3Aoclcnum%2F972636788&rft.isbn=9781509007066&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc1726-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc1726_32-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFC._PartridgeF._Kastenholz1994" class="citation cs1">C. Partridge; F. Kastenholz (December 1994). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1726"><i>Technical Criteria for Choosing IP The Next Generation (IPng)</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC1726">10.17487/RFC1726</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1726">1726</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Technical+Criteria+for+Choosing+IP+The+Next+Generation+%28IPng%29&rft.pub=Network+Working+Group&rft.date=1994-12&rft_id=info%3Adoi%2F10.17487%2FRFC1726&rft.au=C.+Partridge&rft.au=F.+Kastenholz&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc1726&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> </span> </li> <li id="cite_note-rfc791-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc791_33-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJ._Postel1981" class="citation cs1"><a href="/wiki/Jon_Postel" title="Jon Postel">J. Postel</a>, ed. (September 1981). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc791"><i>INTERNET PROTOCOL - DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION</i></a>. <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC0791">10.17487/RFC0791</a></span>. STD 5. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc791">791</a>. IEN 128, 123, 111, 80, 54, 44, 41, 28, 26.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=INTERNET+PROTOCOL+-+DARPA+INTERNET+PROGRAM+PROTOCOL+SPECIFICATION&rft.pub=IETF&rft.date=1981-09&rft_id=info%3Adoi%2F10.17487%2FRFC0791&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc791&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Internet Standard 5.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc760">760</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1349">1349</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2474">2474</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6864">6864</a>. </span> </li> <li id="cite_note-rfc2474-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc2474_34-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFK._NicholsS._BlakeF._BakerD._Black1998" class="citation cs1">K. Nichols; S. Blake; <a href="/wiki/Fred_Baker_(IETF_chair)" class="mw-redirect" title="Fred Baker (IETF chair)">F. Baker</a>; D. Black (December 1998). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2474"><i>Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC2474">10.17487/RFC2474</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2474">2474</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Definition+of+the+Differentiated+Services+Field+%28DS+Field%29+in+the+IPv4+and+IPv6+Headers&rft.pub=Network+Working+Group&rft.date=1998-12&rft_id=info%3Adoi%2F10.17487%2FRFC2474&rft.au=K.+Nichols&rft.au=S.+Blake&rft.au=F.+Baker&rft.au=D.+Black&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc2474&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1455">1455</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1349">1349</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3168">3168</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3260">3260</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8436">8436</a>. </span> </li> <li id="cite_note-rfc3168-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc3168_35-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFK._RamakrishnanS._FloydD._Black2001" class="citation cs1">K. Ramakrishnan; S. Floyd; D. Black (September 2001). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3168"><i>The Addition of Explicit Congestion Notification (ECN) to IP</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3168">10.17487/RFC3168</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3168">3168</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Addition+of+Explicit+Congestion+Notification+%28ECN%29+to+IP&rft.pub=Network+Working+Group&rft.date=2001-09&rft_id=info%3Adoi%2F10.17487%2FRFC3168&rft.au=K.+Ramakrishnan&rft.au=S.+Floyd&rft.au=D.+Black&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3168&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2481">2481</a>. Updates <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2474">2474</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2401">2401</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc793">793</a>. Updated by <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc4301">4301</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6040">6040</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8311">8311</a>. </span> </li> <li id="cite_note-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-36">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSavage2000" class="citation journal cs1">Savage, Stefan (2000). <a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F347057.347560">"Practical network support for IP traceback"</a>. <i>ACM SIGCOMM Computer Communication Review</i>. <b>30</b> (4): 295–306. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F347057.347560">10.1145/347057.347560</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=ACM+SIGCOMM+Computer+Communication+Review&rft.atitle=Practical+network+support+for+IP+traceback&rft.volume=30&rft.issue=4&rft.pages=295-306&rft.date=2000&rft_id=info%3Adoi%2F10.1145%2F347057.347560&rft.aulast=Savage&rft.aufirst=Stefan&rft_id=https%3A%2F%2Fdoi.org%2F10.1145%252F347057.347560&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc6864-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc6864_37-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJ._Touch2013" class="citation cs1">J. Touch (February 2013). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6864"><i>Updated Specification of the IPv4 ID Field</i></a>. <a href="/wiki/IETF" class="mw-redirect" title="IETF">IETF</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC6864">10.17487/RFC6864</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6864">6864</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Updated+Specification+of+the+IPv4+ID+Field&rft.pub=IETF&rft.date=2013-02&rft_id=info%3Adoi%2F10.17487%2FRFC6864&rft.issn=2070-1721&rft.au=J.+Touch&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc6864&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> Updates <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc791">791</a>, <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc1122">1122</a> and <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc2003">2003</a>. </span> </li> <li id="cite_note-rfc3514-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc3514_38-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFS._Bellovin2003" class="citation cs1"><a href="/wiki/Steven_M._Bellovin" title="Steven M. Bellovin">S. Bellovin</a> (1 April 2003). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3514"><i>The Security Flag in the IPv4 Header</i></a>. Network Working Group. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC3514">10.17487/RFC3514</a></span>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3514">3514</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Security+Flag+in+the+IPv4+Header&rft.pub=Network+Working+Group&rft.date=2003-04-01&rft_id=info%3Adoi%2F10.17487%2FRFC3514&rft.au=S.+Bellovin&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc3514&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> This is an <a href="/wiki/April_Fools%27_Day_Request_for_Comments" title="April Fools' Day Request for Comments">April Fools' Day Request for Comments</a>. </span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBhardwaj2020" class="citation web cs1">Bhardwaj, Rashmi (2020-06-04). <a rel="nofollow" class="external text" href="https://ipwithease.com/fragmentation-offset/">"Fragment Offset - IP With Ease"</a>. <i>ipwithease.com</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2022-11-21</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=ipwithease.com&rft.atitle=Fragment+Offset+-+IP+With+Ease&rft.date=2020-06-04&rft.aulast=Bhardwaj&rft.aufirst=Rashmi&rft_id=https%3A%2F%2Fipwithease.com%2Ffragmentation-offset%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.faqs.org/faqs/cisco-networking-faq/section-23.html">"Cisco unofficial FAQ"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2012-05-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Cisco+unofficial+FAQ&rft_id=http%3A%2F%2Fwww.faqs.org%2Ffaqs%2Fcisco-networking-faq%2Fsection-23.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span></span> </li> <li id="cite_note-rfc6274-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-rfc6274_42-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFF._Gont2011" class="citation cs1">F. Gont (July 2011). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6274"><i>Security Assessment of the Internet Protocol Version 4</i></a>. <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC6274">10.17487/RFC6274</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc6274">6274</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Security+Assessment+of+the+Internet+Protocol+Version+4&rft.pub=Internet+Engineering+Task+Force&rft.date=2011-07&rft_id=info%3Adoi%2F10.17487%2FRFC6274&rft.issn=2070-1721&rft.au=F.+Gont&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc6274&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Informational.</i> </span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=IPv4&action=edit&section=23" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Wikidata-logo.svg/40px-Wikidata-logo.svg.png" decoding="async" width="40" height="22" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Wikidata-logo.svg/60px-Wikidata-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/ff/Wikidata-logo.svg/80px-Wikidata-logo.svg.png 2x" data-file-width="1050" data-file-height="590" /></span></span></div> <div class="side-box-text plainlist"><a href="/wiki/Wikidata" title="Wikidata">Wikidata</a> has the property: <ul><li><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Disc_Plain_blue_dark.svg/4px-Disc_Plain_blue_dark.svg.png" decoding="async" width="4" height="4" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Disc_Plain_blue_dark.svg/6px-Disc_Plain_blue_dark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Disc_Plain_blue_dark.svg/8px-Disc_Plain_blue_dark.svg.png 2x" data-file-width="460" data-file-height="460" /></span></span> <b><i><a href="https://www.wikidata.org/wiki/Property_talk:P3761" class="extiw" title="d:Property talk:P3761">IPv4 routing prefix (P3761)</a></i></b> (see <span class="plainlinks"><a class="external text" href="https://query.wikidata.org/embed.html#SELECT%20%3FWikidata_item_%20%3FWikidata_item_Label%20%3Fvalue%20%3FvalueLabel%20%3FEnglish_Wikipedia_article%20%23Show%20data%20in%20this%20order%0A%7B%0A%09%3FWikidata_item_%20wdt%3AP3761%20%3Fvalue%20.%20%23Collecting%20all%20items%20which%20have%20P3761%20data%2C%20from%20whole%20Wikidata%20item%20pages%0A%09OPTIONAL%20%7B%3FEnglish_Wikipedia_article%20schema%3Aabout%20%3FWikidata_item_%3B%20schema%3AisPartOf%20%3Chttps%3A%2F%2Fen.wikipedia.org%2F%3E%20.%7D%20%23If%20collected%20item%20has%20link%20to%20English%20Wikipedia%2C%20show%20that%0A%09SERVICE%20wikibase%3Alabel%20%7B%20bd%3AserviceParam%20wikibase%3Alanguage%20%22en%22%20%20%7D%20%23Show%20label%20in%20this%20language.%20%22en%22%20is%20English.%20%20%20%0A%7D%0ALIMIT%201000">uses</a></span>)</li></ul></div></div> </div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><style data-mw-deduplicate="TemplateStyles:r1250146164">.mw-parser-output .sister-box .side-box-abovebelow{padding:0.75em 0;text-align:center}.mw-parser-output .sister-box .side-box-abovebelow>b{display:block}.mw-parser-output .sister-box .side-box-text>ul{border-top:1px solid #aaa;padding:0.75em 0;width:217px;margin:0 auto}.mw-parser-output .sister-box .side-box-text>ul>li{min-height:31px}.mw-parser-output .sister-logo{display:inline-block;width:31px;line-height:31px;vertical-align:middle;text-align:center}.mw-parser-output .sister-link{display:inline-block;margin-left:4px;width:182px;vertical-align:middle}@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-v2.svg"]{background-color:white}}</style><div role="navigation" aria-labelledby="sister-projects" class="side-box metadata side-box-right mw-collapsible sister-box sistersitebox plainlinks"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-abovebelow" style="clear: both"> <b>IPv4</b> at Wikipedia's <a href="/wiki/Wikipedia:Wikimedia_sister_projects" title="Wikipedia:Wikimedia sister projects"><span id="sister-projects">sister projects</span></a></div> <div class="side-box-flex mw-collapsible-content"> <div class="side-box-text plainlist"><ul><li><span class="sister-logo"><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/27px-Wiktionary-logo-v2.svg.png" decoding="async" width="27" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/41px-Wiktionary-logo-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/0/06/Wiktionary-logo-v2.svg/54px-Wiktionary-logo-v2.svg.png 2x" data-file-width="391" data-file-height="391" /></span></span></span><span class="sister-link"><a href="https://en.wiktionary.org/wiki/Special:Search/IPv4" class="extiw" title="wikt:Special:Search/IPv4">Definitions</a> from Wiktionary</span></li><li><span class="sister-logo"><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/20px-Commons-logo.svg.png" decoding="async" width="20" height="27" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/40px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span></span><span class="sister-link"><a href="https://commons.wikimedia.org/wiki/Category:IPv4" class="extiw" title="c:Category:IPv4">Media</a> from Commons</span></li><li><span class="sister-logo"><span class="mw-valign-middle" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/27px-Wikiversity_logo_2017.svg.png" decoding="async" width="27" height="22" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/41px-Wikiversity_logo_2017.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Wikiversity_logo_2017.svg/54px-Wikiversity_logo_2017.svg.png 2x" data-file-width="626" data-file-height="512" /></span></span></span><span class="sister-link"><a href="https://en.wikiversity.org/wiki/Special:Search/IPv4" class="extiw" title="v:Special:Search/IPv4">Resources</a> from Wikiversity</span></li></ul></div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://www.iana.org">Internet Assigned Numbers Authority</a> (IANA)</li> <li><a rel="nofollow" class="external text" href="http://www.networksorcery.com/enp/protocol/ip.htm">IP, Internet Protocol</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110514231900/http://www.networksorcery.com/enp/protocol/ip.htm">Archived</a> 2011-05-14 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> — IP Header Breakdown, including specific options</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFC._Perkins2010" class="citation cs1">C. Perkins, ed. (November 2010). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5944"><i>IP Mobility Support for IPv4, Revised</i></a>. <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC5944">10.17487/RFC5944</a></span>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/2070-1721">2070-1721</a>. <a href="/wiki/Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc5944">5944</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IP+Mobility+Support+for+IPv4%2C+Revised&rft.pub=Internet+Engineering+Task+Force&rft.date=2010-11&rft_id=info%3Adoi%2F10.17487%2FRFC5944&rft.issn=2070-1721&rft_id=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc5944&rfr_id=info%3Asid%2Fen.wikipedia.org%3AIPv4" class="Z3988"></span> <i>Proposed Standard.</i> Obsoletes <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222">RFC <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3344">3344</a>.</li> <li><a rel="nofollow" class="external text" href="https://www.iana.org/assignments/ipv4-address-space">Official current state of IPv4/8 allocations, as maintained by IANA</a></li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output 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