Apex domains cannot have CNAME records.
Question and response
Question
dig PROF-OHRANA.ru. NS
Answer
PROF-OHRANA.ru. 3 NS ns4.spaceweb.pro.
PROF-OHRANA.ru. 3 NS ns1.spaceweb.ru.
PROF-OHRANA.ru. 3 NS ns2.spaceweb.ru.
PROF-OHRANA.ru. 3 NS ns3.spaceweb.pro.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0