Apex domains cannot have CNAME records.
Question and response
Question
dig bvub.com. NS
Answer
bvub.com. 5 NS ns51.domaincontrol.com.
bvub.com. 5 NS ns52.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0