Canonical Name records
(CNAMEs) act as aliases for the hostnames they are attached to. CNAMEs
take on the web setting and MX record of their assigned hostname.
What are the advantages
CNAMEs are great
timesavers. Instead of having to create multiple hostnames that contain
the same information, you can create one hostname and then create and
attach multiple CNAMEs to that hostname.
Let's say you want
to create a number of hostnames with the same web presence as www.my-example.com.
Instead of creating separate hostnames and setting up a web presence for
each, you can create CNAMEs for my-example.com and attach them to the
www.my-example.com hostname. Any changes you make to the www hostname
will automatically change all the attached CNAMEs accordingly. This saves
you the trouble of modifying many hostnames individually if, for example,
your website address changed.
Do CNAMEs have
to be attached to hostnames within the same domain?
CNAMEs can be attached
to hostnames within the same domain but they don't have to be. For example,
you can create the CNAME cname1.my-example.com and attach it to a hostname
created from the same my-example.com domain: www.my-example.com. However,
you can also create the CNAME cname2.my-example.com and attach it to a
hostname of another domain such as www.mydomain.com or any other hostname
on the Internet.