ns33.cdns.net has no CNAME records.
Question and response
Question
dig ns33.cdns.net. NS
Answer
The response has no answer records.
Authority
cdns.net. 3600 SOA dns1.cdns.net. admin.communitydns.net. 1772339690 900 400 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0