NAME

hostname − host name resolution description

DESCRIPTION

Hostnames are domains.  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 typically performed by the library routine gethostbyname(3N)). Hostnames are resolved by the internet name resolver in the following fashion.  When using NIS or the host table, the hostname is looked up without modification. 

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 a string matching the input hostname.  The file should consist of lines made up of two strings separated by white-space, 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 match is found between the hostname to be resolved and the first field of a line in the file (uppercase and lowercase are treated as equivalent for 7-bit ASCII), 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.  If the name has not been matched by searching through a list of domains and the name contains a dot, it is looked up without modification.  The default search list includes first the local domain, then its parent domains with at least two 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.  If none of the previous attempts matched, the name would be looked up as Lithium.CChem without any domains appended. 

AUTHOR

hostname was developed by the University of California, Berkeley. 

SEE ALSO

named(1M), gethostbyname(3N), resolver(3N),

RFC 1034, RFC 1035

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992