Apex domains cannot have CNAME records.
Question and response
Question
dig becloudby.com. NS
Answer
becloudby.com. 5 NS u2.hoster.by.
becloudby.com. 5 NS u1.hoster.by.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0