<reference anchor="RFC6555" target="https://www.rfc-editor.org/info/rfc6555"> <front> <title>Happy Eyeballs: Success with Dual-Stack Hosts</title> <author fullname="D. Wing" initials="D." surname="Wing"/> <author fullname="A. Yourtchenko" initials="A." surname="Yourtchenko"/> <date month="April" year="2012"/> <abstract> <t>When a server's IPv4 path and protocol are working, but the server's IPv6 path and protocol are not working, a dual-stack client application experiences significant connection delay compared to an IPv4-only client. This is undesirable because it causes the dual- stack client to have a worse user experience. This document specifies requirements for algorithms that reduce this user-visible delay and provides an algorithm. [STANDARDS-TRACK]</t> </abstract> </front> <seriesInfo name="RFC" value="6555"/> <seriesInfo name="DOI" value="10.17487/RFC6555"/> </reference>