A fully qualified domain name consists of a host and domain name, including top-level domain. For example, www.webopedia.com is a fully qualified domain name. www is the host, webopedia is the second-level domain, and.com is the top level domain.

A FQDN always starts with a host name and continues all the way up to the top-level domain name, so www.parc.xerox.com is also a FQDN.