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