mx.131hb.com has no CNAME records.
Question and response
Question
dig mx.131hb.com. NS
Answer
The response has no answer records.
Authority
131hb.com. 3596 SOA dns.131hb.com. hostmaster.131hb.com. 1843368865 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0