Apex domains cannot have CNAME records.
Question and response
Question
dig ri.carnet.hr. NS
Answer
ri.carnet.hr. 5 NS dns1.carnet.hr.
ri.carnet.hr. 5 NS ns.ri.carnet.hr.
Authority
The response has no authority records.
Additional
ns.ri.carnet.hr. 5 A 161.53.30.133
dns1.carnet.hr. 5 A 161.53.123.2
ns.ri.carnet.hr. 5 AAAA 2001:b68:40ff:0:0:0:30:133
dns1.carnet.hr. 5 AAAA 2001:b68:ff:2:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0