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2 .\" Copyright (c) 2000 Manoj Srivastava <srivasta@debian.org>
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25 .\" Modified, 2002-06-16, Mike Coleman
27 .TH HOSTS 5 2002-06-16 "Debian" "Linux Programmer's Manual"
29 hosts \- The static table lookup for host names
33 This manual page describes the format of the
36 This file is a simple text file that associates IP addresses
37 with hostnames, one line per IP address.
38 For each host a single
39 line should be present with the following information:
42 IP_address canonical_hostname [aliases...]
45 Fields of the entry are separated by any number of blanks and/or
47 Text from a "#" character until the end of the line is
48 a comment, and is ignored.
49 Host names may contain only alphanumeric
50 characters, minus signs ("\-"), and periods (".").
51 They must begin with an
52 alphabetic character and end with an alphanumeric character.
53 Optional aliases provide for name changes, alternate spellings,
54 shorter hostnames, or generic hostnames (for example,
57 The Berkeley Internet Name Domain (BIND) Server implements the
58 Internet name server for UNIX systems.
59 It augments or replaces the
61 file or host name lookup, and frees a host from relying on
63 being up to date and complete.
65 In modern systems, even though the host table has been superseded by
66 DNS, it is still widely used for:
69 Most systems have a small host table containing the name and address
70 information for important hosts on the local network.
72 when DNS is not running, for example during system bootup.
75 Sites that use NIS use the host table as input to the NIS host
77 Even though NIS can be used with DNS, most NIS sites still
78 use the host table with an entry for all local hosts as a backup.
81 Very small sites that are isolated from the network use the host table
83 If the local information rarely changes, and the
84 network is not connected to the Internet, DNS offers little
89 192.168.1.10 foo.mydomain.org foo
90 192.168.1.13 bar.mydomain.org bar
91 146.82.138.7 master.debian.org master
92 209.237.226.90 www.opensource.org
95 Modifications to this file normally take effect immediately,
96 except in cases where the file is cached by applications.
97 .SS "Historical Notes"
98 RFC\ 952 gave the original format for the host table, though it has
101 Before the advent of DNS, the host table was the only way of resolving
102 hostnames on the fledgling Internet.
103 Indeed, this file could be
104 created from the official host data base maintained at the Network
105 Information Control Center (NIC), though local changes were often
106 required to bring it up to date regarding unofficial aliases and/or
108 The NIC no longer maintains the hosts.txt files,
109 though looking around at the time of writing (circa 2000), there are
110 historical hosts.txt files on the WWW.
111 I just found three, from 92,
123 This manual page was written by Manoj Srivastava <srivasta@debian.org>,
124 for the Debian GNU/Linux system.