Apex domains cannot have CNAME records.
Question and response
Question
dig beotel.rs. NS
Answer
beotel.rs. 1 NS ns.beotel.net.
beotel.rs. 1 NS ns.beotel.rs.
Authority
The response has no authority records.
Additional
ns.beotel.rs. 1 A 194.106.162.3
ns.beotel.net. 1 A 194.106.162.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0