Hostnamedomainname

Hostnamedomainname is a descriptive phrase used to denote the fully qualified identification of a networked host, formed by the combination of the device’s host name and its domain name. It is not a formal protocol, but it is a common way to refer to the complete address used to locate a host within a DNS namespace.

The host name is a label assigned to a device within a local network, while the domain name identifies a namespace within DNS, whether on the internet or an enterprise network. The hostnamedomainname is the host name appended with the domain name, joined by a dot. For example, a host named server1 in the example.com domain yields the fully qualified domain name server1.example.com.

Usage applications include DNS resolution, TLS certificate naming, and mail routing, where the fully qualified name provides unambiguous addressing across networks. In smaller networks, devices may be reachable by short host names, but the FQDN ensures global uniqueness and proper routing in many services.

Configuration typically involves setting the host name and the domain suffix on the operating system. On Unix-like systems, this may involve hostnamectl or editing relevant files, and ensuring /etc/hosts contains an entry mapping the IP address to the FQDN. On Windows, the computer name and DNS suffix can be configured through system settings. Proper configuration helps avoid resolution issues and certificate name mismatches.

Relation to DNS: the domain portion is managed by DNS records, and the FQDN resolves to an IP address via DNS. A trailing dot may denote an absolute root in some contexts, though it is often optional in practice. See also: fully qualified domain name, hostname, domain name, DNS.