HOSTNAME(7) UNIX 5.0 (November 21, 1987) HOSTNAME(7)
NAME
hostname - host name resolution description
DESCRIPTION
Hostnames are domains, where a domain is a hierarchical,
dot-separated list of subdomains; for example, the machine
monet, in the Berkeley subdomain of the EDU subdomain of the
ARPANET would be represented as
monet.Berkeley.EDU
(with no trailing dot).
Hostnames are often used with network client and server
programs, which must generally translate the name to an
address for use. (This function is generally performed by
the library routine gethostbyname(3).) Hostnames are
resolved by the internet name resolver in the following
fashion.
If the name consists of a single component, i.e. contains no
dot, and if the environment variable ``HOSTALIASES'' is set
to the name of a file, that file is searched for an string
matching the input hostname. The file should consist of
lines made up of two white-space separated strings, the
first of which is the hostname alias, and the second of
which is the complete hostname to be substituted for that
alias. If a case-sensitive match is found between the
hostname to be resolved and the first field of a line in the
file, the substituted name is looked up with no further
processing.
If the input name ends with a trailing dot, the trailing dot
is removed, and the remaining name is looked up with no
further processing.
If the input name does not end with a trailing dot, it is
looked up in the local domain and its parent domains until
either a match is found or fewer than 2 components of the
local domain remain. For example, in the domain
CS.Berkeley.EDU, the name lithium.CChem will be checked
first as lithium.CChem.CS.Berkeley.EDU and then as
lithium.CChem.Berkeley.EDU. Lithium.CChem.EDU will not be
tried, as the there is only one component remaining from the
local domain.
SEE ALSO
resolver(4), mailaddr(7), RFC883
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