[dns-operations] CNAME points to itself

[John Levine]

>I have found that CNAME can be setup to point to itself (at least in 
>BIND9 it can be).
>
>www.itest.com.          300     IN      CNAME   www.itest.com.
>
>should this be disabled?

There's no point.  How would you prevent this?

 --- (on your nameserver) ---

 www.foo.com. 300 IN CNAME www.bar.com.

 --- (on another nameserver on the other side of the planet) ---

 www.bar.com. 300 IN CNAME www.foo.com.

As others have noted, you have to break CNAME loops when you resolve
names.  You can't prevent them.