In the Domain Name System (DNS), a dotted name that fully identifies a TCP/IP host on the Internet. A fully qualified domain name (FQDN) of a host consists of its host name dotted together with its domain name and any names of subdomains in which the host resides.
FQDNs are used in Uniform Resource Locators (URLs) for accessing Web pages on the Internet and provide an absolute path through the DNS namespace to the target host on which the Web page resides. They are also sometimes called absolute domain names.
For the FQDN server7.microsoft.com, the TCP/IP host name is server7 and its domain is microsoft.com.