Apex domains cannot have CNAME records.
Question and response
Question
dig avmail.ru. NS
Answer
avmail.ru. 4 NS dnsproxy1.fm.nic.ru.
avmail.ru. 4 NS dnsproxy2.fm.nic.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0