smtp3.soneribank.com has no CNAME records.
Question and response
Question
dig smtp3.soneribank.com. NS
Answer
The response has no answer records.
Authority
soneribank.com. 394 SOA bradley.ns.cloudflare.com. dns.cloudflare.com. 2397166954 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0