DNS - CNAME

CNAME records define an alias for canonical name for your server (one defined by an A or AAAA record).

For instance, we could have an A name record defining the "server1" host and then use the "www" as an alias for this host:

server1     IN  A       111.111.111.111
www         IN  CNAME   server1

According to RFC 2181, there must be only one canonical name per alias.