CNAME (Canonical Name) records are often referred to as alias records, as they are used to specify that a domain name is an alias for another domain. For example, the subdomain “www” is usually set up as a CNAME record, so that people who type in your domain name with a www. at the front, will still be directed to your site. Unlike A records, the CNAME record is associated with a domain name rather than an IP address, so if the IP address for the A record of a domain is changed, the CNAME records will not need changed, as they are directed by the A record. CNAME records can also be used for web forwarding, allowing your domain to redirect to any domain of your choosing.
Please note, every CNAME record in a DNS zone must be unique – there can be no other records of any kind with the same subdomain.