1HOSTNAME(7) Miscellaneous Information Manual HOSTNAME(7)
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6 hostname - host name resolution description
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9 Hostnames are domains, where a domain is a hierarchical, dot-separated
10 list of subdomains; for example, the machine monet, in the Berkeley
11 subdomain of the EDU subdomain of the ARPANET would be represented as
12 monet.Berkeley.EDU
13 (with no trailing dot).
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15 Hostnames are often used with network client and server programs, which
16 must generally translate the name to an address for use. (This func‐
17 tion is generally performed by the library routine gethostbyname(3).)
18 Hostnames are resolved by the internet name resolver in the following
19 fashion.
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21 If the name consists of a single component, i.e. contains no dot, and
22 if the environment variable ``HOSTALIASES'' is set to the name of a
23 file, that file is searched for an string matching the input hostname.
24 The file should consist of lines made up of two white-space separated
25 strings, the first of which is the hostname alias, and the second of
26 which is the complete hostname to be substituted for that alias. If a
27 case-sensitive match is found between the hostname to be resolved and
28 the first field of a line in the file, the substituted name is looked
29 up with no further processing.
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31 If the input name ends with a trailing dot, the trailing dot is
32 removed, and the remaining name is looked up with no further process‐
33 ing.
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35 If the input name does not end with a trailing dot, it is looked up in
36 the local domain and its parent domains until either a match is found
37 or fewer than 2 components of the local domain remain. For example, in
38 the domain CS.Berkeley.EDU, the name lithium.CChem will be checked
39 first as lithium.CChem.CS.Berkeley.EDU and then as lithium.CChem.Berke‐
40 ley.EDU. Lithium.CChem.EDU will not be tried, as the there is only one
41 component remaining from the local domain.
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44 gethostbyname(3), resolver(5), mailaddr(7), named(8), RFC883
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484.2 Berkeley Distribution November 21, 1987 HOSTNAME(7)