Apex domains cannot have CNAME records.
Question and response
Question
dig SURNET.RU. NS
Answer
surnet.ru. 5 NS ns2.ural.rt.ru.
surnet.ru. 5 NS ns1.ural.rt.ru.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0