Apex domains cannot have CNAME records.
Question and response
Question
dig KUBAN.RU. NS
Answer
KUBAN.RU. 5 NS adns2.south.rt.RU.
KUBAN.RU. 5 NS ns.KUBAN.RU.
Authority
The response has no authority records.
Additional
ns.kuban.RU. 5 A 178.34.168.30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0