Apex domains cannot have CNAME records.
Question and response
Question
dig vitalac.com.bd. NS
Answer
vitalac.com.bd. 5 NS kinsley.ns.cloudflare.com.
vitalac.com.bd. 5 NS jeff.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0