Source : Free On-Line Dictionary of Computing

canonical name
     
        (CNAME) A host's official name as opposed to an alias.  The
        official name is the first hostname listed for its {Internet
        address} in the hostname database, {/etc/hosts} or the
        {Network Information Service} (NIS) map hosts.byaddr ("hosts"
        for short).  A host with multiple network interfaces may have
        more than one Internet address, each with its own canonical
        name (and zero or more aliases).
     
        You can find a host's canonical name using {nslookup} if you
        say
     
        	set querytype=CNAME
     
        and then type a hostname.
     
        (1994-11-29)