Apex domains cannot have CNAME records.
Question and response
Question
dig premiumwebservice.com. NS
Answer
premiumwebservice.com. 4 NS ns2.premiumwebservice.com.
premiumwebservice.com. 4 NS ns.premiumwebservice.com.
Authority
The response has no authority records.
Additional
ns.premiumwebservice.com. 4 A 139.99.8.200
ns2.premiumwebservice.com. 4 A 51.79.209.221
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0