mx.rnc.Ro has no CNAME records.
Question and response
Question
dig mx.rnc.Ro. NS
Answer
The response has no answer records.
Authority
rnc.Ro. 357 SOA ns-a.rnc.Ro. net-admin.rnc.Ro. 1772060606 36000 14400 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0