Fully Qualified Domain Name


Fully Qualified Domain Name (or FQDN) is a hostname that defines the full tree in the Domain Name System (DNS), including root zone and Top-Level Domain (TLD). By definition, FQDNs must have at least one period . in them to classify as a FQDN so there is no ambiguity in when looking up the DNS value.


Assume we have a value like www.example.com, where:

  • www.example.com: The fully qualified domain name (FQDN) for the hostname
  • www: The unqualified domain name (UQDN) of the hostname you are attempting to resolve
  • example.com: The root zone associated with the host
  • com: The top-level domain (TLD) associated with the hostname