Apex domains cannot have CNAME records.
Question and response
Question
dig prof-ohrana.ru. NS
Answer
prof-ohrana.ru. 5 NS ns1.spaceweb.ru.
prof-ohrana.ru. 5 NS ns3.spaceweb.pro.
prof-ohrana.ru. 5 NS ns2.spaceweb.ru.
prof-ohrana.ru. 5 NS ns4.spaceweb.pro.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0