FQDN

Fully Qualified Domain Name

A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name, 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 at least a second-level domain and a top-level domain. A fully qualified domain name is distinguished by its lack of ambiguity: it can be interpreted only in one way.

The DNS root domain is unnamed which is expressed by having an empty label in the DNS hierarchy, resulting in a fully qualified domain name ending with the top-level domain. However, in some cases the full stop (period) character is required at the end of the fully qualified domain name.

In contrast to a domain name that is fully specified, a domain name that does not include the full path of labels up to the DNS root is often called a partially qualified domain name.