Apex domains cannot have CNAME records.
Question and response
Question
dig stacksoft.RU. NS
Answer
STACKSOFT.RU. 3 NS ns.stacksoft.ru.
STACKSOFT.RU. 3 NS ns2.stacksoft.ru.
Authority
The response has no authority records.
Additional
ns.STACKSOFT.RU. 3 A 217.73.199.113
ns2.STACKSOFT.RU. 3 A 213.152.131.125
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0