hostname(5)hostname(5)NAMEhostname - Host name resolution description
DESCRIPTION
Host names 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
follows: monet.Berkeley.EDU
Notice that there is no trailing dot.
Host names 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 gethostbyname() function.) Host
names are resolved by the Internet name resolver in the following fash‐
ion.
If the name consists of a single component (that is, contains no dot),
and if the HOSTALIASES environment variable is set to the name of a
file, that file is searched for a string matching the input host name.
The file should consist of lines made up of two white-space separated
strings, the first of which is the host name alias, and the second of
which is the complete host name to be substituted for that alias. If a
case-insensitive match is found between the host name 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 process‐
ing.
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 ALSO
Functions: gethostbyname(3)
Commands: named(8)hostname(5)