hostname - host name 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
ARPANET 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 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.Berke-
ley.EDU. Lithium.CChem.EDU will not be tried, as the there is only one component remain-
ing from the local domain.
gethostbyname(3), resolver(5), mailaddr(7), named(8), RFC883
4.2 Berkeley Distribution November 21, 1987 HOSTNAME(7)