mx.skole.hr has no CNAME records.
Question and response
Question
dig mx.skole.hr. NS
Answer
The response has no answer records.
Authority
skole.hr. 1042 SOA ns1.skole.hr. root.skole.hr. 2026022602 16384 2048 1048576 2560
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0