hosts

HOSTS(5)                    Debian GNU/Linux manual                   HOSTS(5)



NAME
       hosts - The static table lookup for host names

SYNOPSIS
       /etc/hosts

DESCRIPTION
       This manual page describes the format of the /etc/hosts file. This file
       is a simple text file that associates IP addresses with hostnames,  one
       line per IP address. For each host a single line should be present with
       the following information:

              IP_address canonical_hostname aliases

       Fields of the entry are separated by any number of  blanks  and/or  tab
       characters.  Text  from  a "#" character until the end of the line is a
       comment, and is ignored.  Host  names  may  contain  only  alphanumeric
       characters, minus signs ("-"), and periods (".").  They must begin with
       an  alphabetic  character  and  end  with  an  alphanumeric  character.
       Aliases  provide  for  name changes, alternate spellings, shorter host-
       names, or generic hostnames (for example, localhost).   The  format  of
       the host table is described in RFC 952.

       The Berkeley Internet Name Domain (BIND) Server implements the Internet
       name server for UNIX systems. It augments or  replaces  the  /etc/hosts
       file  or  host name lookup, and frees a host from relying on /etc/hosts
       being up to date and complete.

       In modern systems, even though the host table has  been  superseded  by
       DNS, it is still widely used for:

       bootstrapping
              Most  systems  have  a  small host table containing the name and
              address information for important hosts on  the  local  network.
              This  is useful when DNS is not running, for example during sys-
              tem bootup.

       NIS    Sites that use NIS use the host table as input to the  NIS  host
              database.  Even  though NIS can be used with DNS, most NIS sites
              still use the host table with an entry for all local hosts as  a
              backup.

       isolated nodes
              Very small sites that are isolated from the network use the host
              table instead of DNS. If the local information  rarely  changes,
              and  the  network  is  not connected to the Internet, DNS offers
              little advantage.

EXAMPLE
        127.0.0.1       localhost
        192.168.1.10    foo.mydomain.org  foo
        192.168.1.13    bar.mydomain.org  bar
        216.234.231.5   master.debian.org      master
        205.230.163.103 www.opensource.org

HISTORICAL NOTE
       Before the advent of DNS, the host table was the only way of  resolving
       hostnames on the fledgling Internet. Indeed, this file could be created
       from the official host data base maintained at the Network  Information
       Control Center (NIC), though local changes were often required to bring
       it up to date regarding unofficial aliases and/or unknown  hosts.   The
       NIC  no  longer maintains the hosts.txt files, though looking around at
       the time of writing (circa 2000), there are historical hosts.txt  files
       on the WWW. I just found three, from 92, 94, and 95.

FILES
       /etc/hosts

SEE ALSO
       hostname(1)  resolver(3), resolver(5), hosts(5), hostname(7), named(8),
       Internet RFC 952

AUTHOR
       This manual page was written by Manoj Srivastava <srivasta@debian.org>,
       for the Debian GNU/Linux system.



Debian                            2002-06-16                          HOSTS(5)