IDN Internationalized Domain Names - Support

<!DOCTYPE html> <html lang="en"> <head> <title>IDN Internationalized Domain Names - Support - NIC Liechtenstein</title> <link rel="stylesheet" type="text/css" href="/export/system/modules/ch.SWITCH.ocms.www/resources/css/slim.css" /> <link rel="stylesheet" type="text/css" href="/export/system/modules/ch.SWITCH.ocms.subsite/resources/css/sub.css" /><link rel="stylesheet" type="text/css" media="all" href="/export/sites/nicli/styles.css" /> <script src="/export/system/modules/ch.SWITCH.ocms.subsite/resources/js-slim/sub-slim.js" type="text/javascript" ></script><meta name="description" content="Domain names with accents and umlauts"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta charset="UTF-8"> <link rel="shortcut icon" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/favicon.ico" type="image/x-icon" /> <link rel="apple-touch-icon" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon.png" /> <link rel="apple-touch-icon" sizes="57x57" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-57x57.png" /> <link rel="apple-touch-icon" sizes="72x72" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-72x72.png" /> <link rel="apple-touch-icon" sizes="76x76" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-76x76.png" /> <link rel="apple-touch-icon" sizes="114x114" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-114x114.png" /> <link rel="apple-touch-icon" sizes="120x120" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-120x120.png" /> <link rel="apple-touch-icon" sizes="144x144" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-144x144.png" /> <link rel="apple-touch-icon" sizes="152x152" href="/export/system/modules/ch.SWITCH.ocms.www/resources/images/site_icons/apple-touch-icon-152x152.png" /> </head> <body> <div class="container"> <div class="swi-subsite-logo-container"> <a href="https://www.switch.ch/en/"><img height="46" width="180" src="/export/system/modules/ch.SWITCH.ocms.www/resources/images/logoHi.png" alt=""></a>  <ul class="nav nav-pills pull-right swi-nav-pills-app-meta hidden-xs"> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">EN <span class="swi-link-caret"></span></a> <ul class="dropdown-menu"> <li><a href="/de/support/idn/">DE</a></li> </ul> </li> </ul>  </div> <nav class="navbar navbar-default swi-navbar-subsite" role="navigation"> <div class="container-fluid">  <div class="navbar-header"> <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1"> <span class="sr-only">Toggle navigation</span> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </button> <a class="navbar-brand" href="/">NIC Liechtenstein</a> </div>  <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1"> <ul class="nav navbar-nav"> <li class=" "> <a href="/whois/">Lookup</a> </li> <li class=" "> <a href="/registrars/">Registrars</a> </li> <li class=" "> <a href="/terms/">Legal Info</a> </li> <li class=" "> <a href="/security/">Security</a> </li> <li class="active "> <a href="/support/">Support</a> </li> <li class=" "> <a href="/statistics/">Statistics</a> </li> <li class=" "> <a href="/about/">About Us</a> </li> <li class="dropdown visible-xs"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">EN <span class="swi-link-caret"></span></a> <ul class="dropdown-menu"> <li><a href="/de/support/idn/">DE</a></li> </ul> </li> </ul> </div> </div> </nav> </div> <div id="jumbotron" > <div>  <div class="jumbotron swi-jumbotron swi-jumbotron-bright-text swi-jumbotron-www swi-jumbotron-noimg"> <div class="container swi-jumbotron-content"> <div class="swi-inner"> <h1 >IDN - Internationalized Domain Names</h1> <p class="lead">Domain names with accents and umlauts</p> </div> </div> </div></div> </div> <div class="container swi-container"> <div class="row"> <div class="col-xs-12 col-sm-8"> <div class="swi-tree visible-xs"> <ul> <li><a href="/support/">Support</a></li> <li><a href="/support/general/">FAQs on Domain Names</a></li> <li class="active"><a href="/support/idn/">IDN Internationalized Domain Names</a></li> <li><a href="/support/glossary/">Glossary</a> </li> </ul> </div> <div id="content" ><div> <div ><p>Domain names under .ch and .li can also contain non-ASCII characters such as umlauts and accents. Such domain names that contain umlauts, other diacritical characters or letters from alphabets other than the Latin alphabet are referred to as Internationalized Domain Names (IDN). The characters permitted for .ch and .li domain names are listed in <strong><a href="http://www.nic.ch/terms/agb/#anhang">Annexes 1 and 2 of the GTC</a></strong>.</p></div></div> <div> <div class="panel-group acc-v2" id="accordion-b1c4c7ce-dc91-11e5-a924-525400a7a801"> <div class="panel panel-default"> <div class="panel-heading"> <h4 class="panel-title"> <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion-b1c4c7ce-dc91-11e5-a924-525400a7a801" href="#collapse-b1c4c7ce-dc91-11e5-a924-525400a7a801-1"> Technical solution </a> </h4> </div> <div id="collapse-b1c4c7ce-dc91-11e5-a924-525400a7a801-1" class="panel-collapse collapse" style="height: auto;"> <div class="panel-body" ><div> <div ><h4>ACE string</h4> <p>There were essentially two different options open for introducing internationalized domain names (IDN). The first was to make adjustments to the domain name system (DNS) which would allow unicode characters to be used directly. It was felt that this was too drastic a measure, and hence the second option was chosen. This involved compiling an algorithm to specify how a unicode string should be converted into a permitted ASCII domain name. This ACE string (ACE stands for ASCII Compatible Encoding) is <span class="CmCaReT" style="display: none;">�</span>then entered into the DNS. The introduction of IDN means that, for the very first time, the entry in the DNS is no longer identical with the domain name.</p> <h4>Name Preparation, Punycode</h4> <p>A number of requirements have to be fulfilled before a unicode string can be converted into an ACE string. This is done by the so-called "Nameprep" procedure, which makes sure that no inadmissible characters are included. Umlauts which are made up of two characters have to be replaced by a single character, e.g. <strong>a</strong> + <strong>¨</strong> = <strong>ä</strong>. This process is referred to as "normalization". In addition, all big Latin letters are converted into small letters. This is known as "case mapping" or "case folding".</p> <p>If non-ASCII characters are contained in the string after the "name preparation" has been run through, the system places the prefix xn-- in front of this string. Punycode takes the non-ASCII characters out of the actual domain name, notes their position, and adds them on at the end of the name again, in coded form, separated by means of a further hyphen.</p> <h5>An example</h5> <p><img style="width: 530px;" src="/export/shared/.content/images/idnexample-en.gif" alt="" /></p> <h4>Consequences</h4> <p>The domain name and the entry in the DNS are two different things with IDN.</p> <p><strong>bücher.ch</strong> is the domain name, <strong> <br /> xn--bcher-kva.ch</strong> is the ACE string, and it is this string that is entered in the DNS.</p> <p>For technical reasons, the character string that has been processed by the algorithm is several characters longer than the domain name itself. The domain name "www.buecher.ch" is seven characters long. The corresponding ACE string, however, is 13 characters long.</p> <p><strong>bücher.ch</strong> = domain name = must be at least three characters long, <br /> <strong>xn--bcher-kva.ch</strong> = DNS entry = may be a maximum of 63 characters long.</p> <h4>IETF Standards</h4> <ul class="list-unstyled"> <li><a href="http://tools.ietf.org/html/rfc3492">RFC 3492</a> Encoding Scheme (Punycode)</li> <li><a href="http://tools.ietf.org/html/rfc5890">RFC 5890</a> IDNA (Internationalized Domain Names for Applications): Framework</li> <li><a href="http://tools.ietf.org/html/rfc5891">RFC 5891</a> IDNA: Protocol</li> <li><a href="http://tools.ietf.org/html/rfc5892">RFC 5892</a> IDNA: Unicode Code Points</li> <li><a href="http://tools.ietf.org/html/rfc5893">RFC 5893</a> IDNA: Right-to-Left Scripts</li> <li><a href="http://tools.ietf.org/html/rfc5894">RFC 5894</a> IDNA: Background, Explanations, and Rationale</li> </ul></div></div> </div> </div> </div> <div class="panel panel-default"> <div class="panel-heading"> <h4 class="panel-title"> <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion-b1c4c7ce-dc91-11e5-a924-525400a7a801" href="#collapse-b1c4c7ce-dc91-11e5-a924-525400a7a801-2"> Support in programs </a> </h4> </div> <div id="collapse-b1c4c7ce-dc91-11e5-a924-525400a7a801-2" class="panel-collapse collapse" style="height: 0px;"> <div class="panel-body" ><div> <div ><p>Current browsers and e-mail programmes support IDNs. However, you should not rely solely on an IDN for important applications.</p> <p>Switch does not guarantee that domain names with umlauts and accents as per Annex 2 of the GTC are suitable for use in conjunction with programs such as browsers and e-mail programs and does not accept any liability in this respect.</p></div></div> </div> </div> </div> </div> </div></div> </div> <div class="col-xs-12 col-sm-4 swi-subsite-sidebar"> <div class="swi-tree hidden-xs"> <ul> <li><a href="/support/">Support</a></li> <li><a href="/support/general/">FAQs on Domain Names</a></li> <li class="active"><a href="/support/idn/">IDN Internationalized Domain Names</a></li> <li><a href="/support/glossary/">Glossary</a> </li> </ul> </div> <div id="context" > <div>  <div class="swi-sidebar-box swi-sidebar-box-grey"> <div class="swi-inner"> <div><h3 >Registrars for .li</h3></div> <div ><p><strong>Registering new .li domain names:</strong> Please select a registrar. <br /><strong>Already registered domain names: </strong>Please contact the registrar administering your domain name for any changes.</p></div> <a class="noicon btn btn-default swi-btn" href="/registrars/">List of all Registrars</a> </div> </div> </div> <div>  <div class="swi-sidebar-box swi-sidebar-box-grey"> <div class="swi-inner"> <div><h3 >Domain Name Lookup</h3></div> <div ><p>Is the domain name you want still available?</p> <p>Who is the registrar of your domain name?</p></div> <a class="noicon btn btn-default swi-btn" href="/whois/">Domain Name Lookup</a> </div> </div> </div> </div> </div> </div> </div> <footer class="swi-footer-bottom swi-footer-bottom-subsite hidden-print"> <div class="container clearfix"> <div class="swi-footer-breadcrumb pull-left"> <ol class="breadcrumb"> <li><a href="/about/disclaimer/">Legal notice</a></li> <li><a href="/about/imprint/">Imprint</a></li> </ol> </div> <div class="swi-footer-copyright-subsite pull-right"> © 2025 for content at Switch </div> </div> </footer>  <script type="text/javascript"> var _paq = _paq || []; _paq.push(['trackPageView']); _paq.push(['enableLinkTracking']); (function() { var u=(("https:" == document.location.protocol) ? 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IDN Internationalized Domain Names - Support - NIC Liechtenstein