HOSTNAME(7) Linux Programmer's Manual HOSTNAME(7)
hostname - hostname resolution 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 Internet would be represented as
(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
task is generally performed by either getaddrinfo(3) or the obsolete gethostbyname(3).) Hostnames are resolved by the Internet name
resolver in the following fashion.
If the name consists of a single component, that is, contains no dot, and if the environment variable HOSTALIASES is set to the name of a
file, that file is searched for any string matching the input hostname. The file should consist of lines made up of two white-space sepa-
rated 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-insensitive 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 by searching through a list of domains until a match is found. The
default search list includes first the local domain, then its parent domains with at least 2 name components (longest first). 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 there is only one component remaining from the local domain. The
search path can be changed from the default by a system-wide configuration file (see resolver(5)).
gethostbyname(3), resolver(5), mailaddr(7), named(8)
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2008-06-11 HOSTNAME(7)