Apex domains cannot have CNAME records.
Question and response
Question
dig unic.kg.ac.rs. NS
Answer
unic.kg.ac.rs. 5 NS ns.unic.kg.ac.rs.
unic.kg.ac.rs. 5 NS ns1.unic.kg.ac.rs.
Authority
The response has no authority records.
Additional
ns.unic.kg.ac.rs. 5 A 147.91.209.2
ns1.unic.kg.ac.rs. 5 A 147.91.209.20
ns.unic.kg.ac.rs. 5 AAAA 2001:4170:3000:1:0:0:0:2
ns1.unic.kg.ac.rs. 5 AAAA 2001:4170:3000:1:0:0:0:20
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0