hostname - Host name resolution description
Host names are domains, where a domain is a hierarchical, dot-separated
list of subdomains; for example, the machine monet, in the Berkeley sub-
domain of the EDU subdomain of the Internet would be represented as fol-
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 fashion.
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 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 remain-
ing from the local domain. The search path can be changed from the default
by a system-wide configuration file.