Apex domains cannot have CNAME records.
Question and response
Question
dig yourdomain.com. NS
Answer
yourdomain.com. 5 NS ns03.domaincontrol.com.
yourdomain.com. 5 NS ns04.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0