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