Apex domains cannot have CNAME records.
Question and response
Question
dig cdngp.net. NS
Answer
cdngp.net. 5 NS ns1.cdnetdns.net.
cdngp.net. 5 NS ns2.cdnetdns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0