mx.CARNet.hr has no CNAME records.
Question and response
Question
dig mx.CARNet.hr. NS
Answer
The response has no answer records.
Authority
CARNet.hr. 294 SOA dns1.CARNet.hr. hostmaster.CARNet.hr. 2026022201 10800 3600 2419200 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0