Apex domains cannot have CNAME records.
Question and response
Question
dig LONG-EDU.RU. NS
Answer
LONG-EDU.RU. 4 NS ns2.hosting.reg.RU.
LONG-EDU.RU. 4 NS ns1.hosting.reg.RU.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0