Editing Fully qualified domain name (section)

==Usage==
Dot-separated fully qualified domain names are the primarily used form for human-readable representations of a domain name. Dot-separated domain names are not used in the internal representation of labels in a DNS message<ref>{{cite web |title=Wireshark Q&A |url=https://osqa-ask.wireshark.org/questions/50806/help-understanding-dns-packet-data/ |website=osqa-ask.wireshark.org |access-date=13 April 2021 |archive-date=13 April 2021 |archive-url=https://web.archive.org/web/20210413010527/https://osqa-ask.wireshark.org/questions/50806/help-understanding-dns-packet-data/ |url-status=live }}</ref> but are used to reference domains in some [[TXT record|TXT records]] and can appear in [[resolver (DNS)|resolver]] configurations, system [[hosts (file)|hosts files]], and [[URLs]].

Web addresses typically use FQDNs to represent the host, as it ensures the address will be interpreted identically on any network. Relative hostnames are allowed by some protocols, including [[HTTP]], but disallowed by others, such as the [[Simple Mail Transfer Protocol]] (SMTP).<ref>{{cite web |url=http://tools.ietf.org/html/rfc5321#section-2.3.5 |title=Definition of domain names in Simple Mail Transfer Protocol |publisher=Tools.ietf.org |date=21 May 1998 |access-date=8 January 2014 |archive-date=30 December 2013 |archive-url=https://web.archive.org/web/20131230053037/http://tools.ietf.org/html/rfc5321#section-2.3.5 |url-status=live |last1=Klensin |first1=John C. }}</ref>