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man:hosts

HOSTS(5) Linux Programmer's Manual HOSTS(5)

NAME

     hosts - static table lookup for hostnames

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 hostname 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     In  modern  systems,  even though the host table has been superseded by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.

FILES

     /etc/hosts

NOTES

     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  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 historical
     hosts.txt files on the WWW.  I just found three, from 92, 94, and 95.

EXAMPLE

     # The following lines are desirable for IPv4  capable  hosts  127.0.0.1
     localhost
     #  127.0.1.1  is  often  used  for  the  FQDN  of the machine 127.0.1.1
     thishost.mydomain.org    thishost   192.168.1.10       foo.mydomain.org
     foo  192.168.1.13     bar.mydomain.org        bar  146.82.138.7    mas-
     ter.debian.org      master 209.237.226.90  www.opensource.org
     # The  following  lines  are  desirable  for  IPv6  capable  hosts  ::1
     localhost   ip6-localhost   ip6-loopback  ff02::1          ip6-allnodes
     ff02::2         ip6-allrouters

SEE ALSO

     hostname(1), resolver(3),  host.conf(5),  resolv.conf(5),  resolver(5),
     hostname(7), named(8)
     Internet RFC 952

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.

Linux 2017-09-15 HOSTS(5)

/data/webs/external/dokuwiki/data/pages/man/hosts.txt · Last modified: 2019/05/17 09:47 by 127.0.0.1

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