hosts

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	host-
       names,  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 Inter-
       net 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       In modern systems, even though the host table has been  superseded  by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 cre-
       ated from the official host data base maintained at the Network Infor-
       mation  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 histori-
       cal  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	<sri-
       vasta@debian.org>, for the Debian GNU/Linux system.



Debian				  2002-06-16			     HOSTS(5)