Apex domains cannot have CNAME records.
Question and response
Question
dig 0.61.178.195.in-addr.arpa. NS
Answer
0.61.178.195.in-addr.arpa. 5 NS ODISEJ.TELEKOM.RS.
0.61.178.195.in-addr.arpa. 5 NS NS.ETF.BG.AC.RS.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0