Apex domains cannot have CNAME records.
Question and response
Question
dig RSNX.RU. NS
Answer
rsnx.ru. 5 NS sns1.rsnx.ru.
rsnx.ru. 5 NS sns2.rsnx.ru.
Authority
The response has no authority records.
Additional
sns1.rsnx.RU. 5 A 89.253.252.11
sns2.rsnx.RU. 5 A 195.2.69.96
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0