Apex domains cannot have CNAME records.
Question and response
Question
dig it-grad.RU. NS
Answer
it-grad.RU. 4 NS bns.mws.RU.
it-grad.RU. 4 NS cns.mws-mts.net.
it-grad.RU. 4 NS ens.mws.RU.
it-grad.RU. 4 NS ans.mws-mts.net.
Authority
The response has no authority records.
Additional
ans.mws-mts.net. 4 A 176.109.73.19
bns.mws.ru. 4 A 213.87.46.68
cns.mws-mts.net. 4 A 213.87.75.213
ens.mws.ru. 4 A 217.8.236.201
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0