FQDN is an abbreviation of Fully Qualified Domain Name, and it stands for the most complete domain name for a specific website, computer or server on the Internet. It is also known as the absolute domain name. Where a domain name consists of a registered name plus a domain extension (top level domains), an FQDN is the full name including any subdomains such as “www” in the FQDN “www.thingsdata.nl”.

In combination with a protocol such as HTTP(S) and a possible file location, an FQDN forms a URL. The IP address associated with an FQDN is looked up via the Domain Name System (DNS). For example, it is possible to set up a connection to a server on the basis of an FQDN.