Apex domains cannot have CNAME records.
Question and response
Question
dig site.pro. NS
Answer
site.pro. 5 NS ns3.site.pro.
site.pro. 5 NS ns2.site.pro.
site.pro. 5 NS ns1.site.pro.
site.pro. 5 NS ns4.site.pro.
Authority
The response has no authority records.
Additional
ns1.site.pro. 5 A 3.67.159.130
ns2.site.pro. 5 A 35.196.50.58
ns3.site.pro. 5 A 52.67.222.115
ns4.site.pro. 5 A 92.255.76.133
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0