Apex domains cannot have CNAME records.
Question and response
Question
dig orion.rs. NS
Answer
orion.rs. 5 NS auth2.oriontelekom.com.
orion.rs. 5 NS auth4.oriontelekom.com.
orion.rs. 5 NS ns61.orion.rs.
orion.rs. 5 NS auth1.oriontelekom.com.
orion.rs. 5 NS ns62.orion.rs.
orion.rs. 5 NS auth3.oriontelekom.com.
Authority
The response has no authority records.
Additional
auth1.oriontelekom.com. 5 A 77.105.36.34
auth2.oriontelekom.com. 5 A 77.105.37.0
auth3.oriontelekom.com. 5 A 169.60.35.162
auth4.oriontelekom.com. 5 A 43.239.97.50
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0