Hostname

A hostname is a label assigned to a device on a network that identifies it among other devices. It is typically a short, human‑readable name chosen by an administrator or user and is used in network communications and administration.

In the Domain Name System, a hostname may form part of a fully qualified domain name (FQDN). The FQDN is a complete domain name that resolves to an IP address, for example host.example.com. The hostname alone identifies the device within its local network; the domain name provides its position within the global DNS hierarchy.

Local networks may use simple hostnames that are unique within that network. On the internet, hostnames are registered in DNS and must be globally unique within the domain. Hostname resolution is performed by DNS queries or local host tables. Hostnames can be assigned statically or obtained dynamically via DHCP or other services.

On Linux, the hostname is stored in /etc/hostname and may be managed with hostnamectl or set via the hostname command; /etc/hosts may map hostnames to IP addresses. On Windows, the computer name can be set in System properties or via the net config. DHCP servers may update DNS records with dynamic updates (DDNS).

Valid hostnames must comply with syntax restrictions: each label up to 63 characters, and the full domain name up to 253 characters. Labels use letters, digits, and hyphens, but must not start or end with a hyphen. Hostnames are typically case-insensitive.