Apex domains cannot have CNAME records.
Question and response
Question
dig bisv.ru. NS
Answer
bisv.ru. 5 NS ns.datapark.ru.
bisv.ru. 5 NS ns2.bisv.ru.
bisv.ru. 5 NS ns1.bisv.ru.
Authority
The response has no authority records.
Additional
ns1.bisv.ru. 5 A 93.190.18.10
ns2.bisv.RU. 5 A 93.190.19.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0