Apex domains cannot have CNAME records.
Question and response
Question
dig sbb.exchange. NS
Answer
sbb.exchange. 5 NS ns2.cpanelhosting.rs.
sbb.exchange. 5 NS ns3.cpanelhosting.rs.
sbb.exchange. 5 NS ns1.cpanelhosting.rs.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0