Apex domains cannot have CNAME records.
Question and response
Question
dig snva.ca.megapath.net. NS
Answer
snva.ca.megapath.net. 5 NS ns3.covad.com.
snva.ca.megapath.net. 5 NS ns1.covad.com.
snva.ca.megapath.net. 5 NS ns2.covad.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0