CNAME means Canonical name. This record is used to define multiple domain names for a single system.
If several services are running on a single system and every service needs its domain, the CNAME record is used for that.
For example, if a web server and FTP server are running on the same system, there has to be created CNAMEs for both of them.
System name - system1.abc.com
Web server - www.abc.com
FTP server - ftp.system1.com
The most common use of the CNAME is to provide access to a single web server using the standard "www.domain.com" and "domain.com" (with and without "www"). In the case of renaming a domain, this setup can be used also to redirect the old name of the webserver to the new one.
To avoid circular references, the CNAME should always point to a real hostname and never to another CNAME.
In Cloudimage, you can add CNAMEs from the Admin panel -> Image Settings -> Domains tab:
without Alias - //doc.cloudimg.io/v7/http://sample.li/boat.jpg?width=800
with Alias - //doc.cloudimg.io/v7/_sample_/boat.jpg?width=800
In Cloudimage, you can add Aliases from the Admin panel -> Image Settings -> Domains tab: