CNAME-records are domain name aliases. Often computers on the Internet have multiple functions. To mask this, CNAME-records can be used to give a single computer multiple names (aliases). For example computer "xyz.com" may be both a web-server and an ftp-server, so two CNAME-records are defined: "www.xyz.com" = "xyz.com" and "ftp.xyz.com" = "xyz.com". A CNAME-record should always point to an A-record to avoid circular references.

The most popular use of the CNAME-record type is to provide access to a web-server using both the standard "www.domain.com" and "domain.com" (without the www). This is usually done by creating an A-record for the short name (without www), and a CNAME-record for the www name pointing to the short name.