Apex domains cannot have CNAME records.
Question and response
Question
dig net.ru. NS
Answer
net.ru. 5 NS e.dns-servers.net.ru.
net.ru. 5 NS d.dns-servers.net.ru.
net.ru. 5 NS a.dns-servers.net.ru.
net.ru. 5 NS f.dns-servers.net.ru.
net.ru. 5 NS b.dns-servers.net.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0