Apex domains cannot have CNAME records.
Question and response
Question
dig opcom.ru. NS
Answer
opcom.ru. 4 NS ns2.opcom.ru.
opcom.ru. 4 NS ns1.opcom.ru.
Authority
The response has no authority records.
Additional
ns1.opcom.ru. 4 A 62.122.199.253
ns2.opcom.ru. 4 A 62.122.198.253
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0