Apex domains cannot have CNAME records.
Question and response
Question
dig nunsys.com. NS
Answer
nunsys.com. 5 NS ns2.nunsys.com.
nunsys.com. 5 NS ns1.nunsys.com.
Authority
The response has no authority records.
Additional
ns1.nunsys.com. 5 A 185.5.236.10
ns2.nunsys.com. 5 A 74.234.33.120
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0