Apex domains cannot have CNAME records.
Question and response
Question
dig BNNIC.BN. NS
Answer
bnnic.bn. 5 NS ns204.brunet.bn.
bnnic.bn. 5 NS ns104.brunet.bn.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0