Apex domains cannot have CNAME records.
Question and response
Question
dig msk-ix.ru. NS
Answer
msk-ix.ru. 5 NS ns.msk-ix.ru.
msk-ix.ru. 5 NS int3.ix.ru.
msk-ix.ru. 5 NS int2.ix.ru.
Authority
The response has no authority records.
Additional
ns.msk-ix.ru. 5 A 194.226.65.9
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0