Apex domains cannot have CNAME records.
Question and response
Question
dig zolotoff.ru. NS
Answer
zolotoff.ru. 5 NS belgorod.ens.mail.ru.
zolotoff.ru. 5 NS derbent.ens.mail.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0