Apex domains cannot have CNAME records.
Question and response
Question
dig rasnet.ru. NS
Answer
rasnet.ru. 5 NS ns1.rasnet.ru.
rasnet.ru. 5 NS ns.rasnet.ru.
Authority
The response has no authority records.
Additional
ns.rasnet.ru. 5 A 83.149.239.161
ns1.rasnet.ru. 5 A 83.149.192.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0