Apex domains cannot have CNAME records.
Question and response
Question
dig RBC.RU. NS
Answer
RBC.RU. 5 NS ns2.RBC.RU.
RBC.RU. 5 NS ns3.RBC.RU.
Authority
The response has no authority records.
Additional
ns2.rbc.ru. 5 A 185.72.229.26
ns3.rbc.ru. 5 A 80.68.253.26
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0