In computer networking, a hostname (archaically nodename) is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication such as the World Wide Web, e-mail or Usenet. Hostnames may be simple names consisting of a single word or phrase, or they may be structured.

On the Internet, hostnames may have appended the name of a Domain Name System (DNS) domain, separated from the host-specific label by a period ("dot"). In the latter form, a hostname is also called a domain name. If the domain name is completely specified, including a top-level domain of the Internet, then the hostname is said to be a fully qualified domain name (FQDN). Hostnames that include DNS domains are often stored in the Domain Name System together with the IP addresses of the host they represent for the purpose of mapping the hostname to an address, or the reverse process.

Overview

Hostnames are human-readable nicknames that correspond to the address of a device connected to a network. They are used by various naming systems, e.g., Network Information Service (NIS), Domain Name System (DNS), Server Message Block (SMB), and the meaning of hostname will vary according to the naming system used. A hostname meaningful to a Microsoft NetBIOS workgroup may be an invalid Internet hostname. When presented with a hostname without any context, it is usually safe to assume that the network is the Internet and the hostname's naming system is the DNS.