Stands for Canonical Name record, a Domain Name System (DNS) resource record in a DNS server's database or zone file. A CNAME record is used to map an alias to the canonical name (true name) of a server. The CNAME record lets you use more than one name to refer to a single host on the network.
If a name server is queried by a resolver to look up a host and the queried name is an alias in a CNAME record, the name server replaces the alias name with the canonical name of the host being looked up, and then looks up the address of the canonical name.
Here is an address record for the host named server12 in the Microsoft.com Internet domain. This record has the IP address 172.16.8.5, followed by a CNAME record indicating that the name bobby (or the fully qualified domain name bobby.Microsoft.com) is an alias for the same host:
server12.Microsoft.com IN A 172.16.8.55
bobby IN CNAME server12