Apex domains cannot have CNAME records.
Question and response
Question
dig sanwell.biz. NS
Answer
sanwell.biz. 5 NS NS1.101DOMAIN.COM.
sanwell.biz. 5 NS NS2.101DOMAIN.COM.
sanwell.biz. 5 NS NS5.101DOMAIN.COM.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0