mail.vrcodingdna.com has no CNAME records.
Question and response
Question
dig mail.vrcodingdna.com. NS
Answer
The response has no answer records.
Authority
vrcodingdna.com. 6576 SOA ns.vrcodingdna.com. cdna-nok.rotzefull.de. 1760000973 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0