HOSTS(5)

NAME
hosts - host name database

DESCRIPTION
The hosts file contains information regarding the known hosts on the network. For each host, a single line should be present with the following information:

    Internet address
    Official host name
    Aliases

Items are separated by any number of blanks and/or tab characters. A ‘#’ indicates the beginning of a comment; characters up to the end of the line are not interpreted by routines which search the file.

The system configuration file resolv.conf(5) controls where host name information will be searched for. The mechanism provided permits the administrator to describe the databases to search; the databases currently known include yp(8), DNS and the hosts database.

When using the name server named(8), this file provides a backup when the name server is not running. For the name server, it is suggested that only a few addresses be included in this file. These include addresses for the local interfaces that ifconfig(8) needs at boot time and a few machines on the local network.

This file may be created from the official host database maintained at the Network Information Control Center (NIC), though local changes may be required to bring it up to date regarding unofficial aliases and/or unknown hosts. As the database maintained at NIC is incomplete, use of the name server is recommended for sites on the DARPA Internet.

Internet addresses are specified using either dot notation (IPv4) or colon separated notation (IPv6). Further information on network addressing is contained in inet(3). Host names may contain any printable character other than a field delimiter, newline, or comment character.

FILES
/etc/hosts

SEE ALSO
getaddrinfo(3), gethostbyname(3), getnameinfo(3), inet(3), resolv.conf(5), ifconfig(8), named(8) Name Server Operations Guide for BIND.

HISTORY
The hosts file format appeared in 4.2BSD.

BUGS
A name server should be used instead of a static file.

Lines in /etc/hosts are limited to BUFSIZ characters (currently 1024). Longer lines will be ignored.