Apex domains cannot have CNAME records.
Question and response
Question
dig bn.md. NS
Answer
bn.md. 5 NS ns.nscluster.wf.
bn.md. 5 NS ns.nscluster.eu.
bn.md. 5 NS ns-cloud-b4.googledomains.com.
bn.md. 5 NS ns-cloud-b3.googledomains.com.
Authority
The response has no authority records.
Additional
ns.nscluster.eu. 5 A 188.166.70.123
ns.nscluster.wf. 5 A 45.153.185.71
ns.nscluster.eu. 5 AAAA 2a03:b0c0:2:d0:0:0:79d:4001
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0