smtp5.cvcpaging.com has no CNAME records.
Question and response
Question
dig smtp5.cvcpaging.com. NS
Answer
The response has no answer records.
Authority
cvcpaging.com. 1600 SOA adel.ns.cloudflare.com. dns.cloudflare.com. 2397019552 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0