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 hostnamewww: The unqualified domain name (UQDN) of the hostname you are attempting to resolveexample.com: The root zone associated with the hostcom: The top-level domain (TLD) associated with the hostname