Fully qualified domain name

A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name,^[1] is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS). It specifies all domain levels, including the top-level domain and the root zone.^[2] A fully qualified domain name is distinguished by its lack of ambiguity in terms of DNS zone location in the hierarchy of DNS labels: it can be interpreted only in one way.

^ Mockapetris, Paul. Domain names – Implementation and Specification. doi:10.17487/RFC1035. RFC 1035.
^ April N. Marine; Joyce K. Reynolds; Gary Scott Malkin (March 1994). "Questions About the Domain Name System". Answers to Commonly asked "New Internet User" Questions. IETF. sec. 5. doi:10.17487/RFC1594. RFC 1594. Retrieved 29 April 2013. If you think of the DNS as a tree-structure with each node having its own label, a fully qualified domain name for a specific node would be its label followed by the labels of all the other nodes between it and the root of the tree.

[RFC1035-1] Mockapetris, Paul. Domain names – Implementation and Specification. doi:10.17487/RFC1035. RFC 1035.

[2] April N. Marine; Joyce K. Reynolds; Gary Scott Malkin (March 1994). "Questions About the Domain Name System". Answers to Commonly asked "New Internet User" Questions. IETF. sec. 5. doi:10.17487/RFC1594. RFC 1594. Retrieved 29 April 2013. If you think of the DNS as a tree-structure with each node having its own label, a fully qualified domain name for a specific node would be its label followed by the labels of all the other nodes between it and the root of the tree.

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