Apex domains cannot have CNAME records.
Question and response
Question
dig supremedns.com. NS
Answer
supremedns.com. 5 NS ns1.supremedns.com.
supremedns.com. 5 NS ns2.supremedns.com.
Authority
The response has no authority records.
Additional
ns1.supremedns.com. 5 A 198.23.53.28
ns2.supremedns.com. 5 A 198.23.53.30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0