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HOSTS(5)		   Linux Programmer's 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.
       Optional aliases provide for name changes, alternate spellings, shorter
       hostnames, or generic hostnames (for example, localhost).

       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       In  modern  systems,  even though the host table has been superseded by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
	146.82.138.7	master.debian.org      master
	209.237.226.90	www.opensource.org

NOTE
       Modifications  to this file normally take effect immediately, except in
       cases where the file is cached by applications.

HISTORICAL NOTES
       RFC 952 gave the original format for the	 host  table,  though  it  has
       since changed.

       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), 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)
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