The CNAME record is also known as canonical name record. It is used for specifying that a domain name is an alias for another domain, the “canonical” domain. The CNAME Record is used only for subdomains. You can’t add any other records for given hostname, if this hostname has a CNAME Record. Also, it’s not possible to create CNAME record if there are any other records for this hostname.
The canonical name record becomes useful when you want to direct users to the same information delivered on a separate url. For example, for website owners who use a domain such as yourwebsite.com without any subdomain, a canonical name can be used to add www to the beginning of the URL. Therefore, when a user accesses your site via www.yourwebsite.com, they will see the same information as if they accessed it via yourwebsite.com.