Apex domains cannot have CNAME records.
Question and response
Question
dig mkrovlya.ru. NS
Answer
mkrovlya.ru. 5 NS ns3.mkrovlya.ru.
mkrovlya.ru. 5 NS ns1.mkrovlya.ru.
Authority
The response has no authority records.
Additional
ns1.mkrovlya.ru. 5 A 46.0.199.208
ns3.mkrovlya.ru. 5 A 213.178.54.62
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0