mail.ninenic.com has no CNAME records.
Question and response
Question
dig mail.ninenic.com. NS
Answer
The response has no answer records.
Authority
ninenic.com. 9044 SOA ns.ninenic.com. info.ecomsiam.com. 2018032716 86400 7200 21600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0