Apex domains cannot have CNAME records.
Question and response
Question
dig kontur.host. NS
Answer
kontur.host. 4 NS b2.ns.ix.ru.
kontur.host. 4 NS a2.ns.ix.ru.
kontur.host. 4 NS ns8-l2.nic.ru.
kontur.host. 4 NS ns4-l2.nic.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0