Apex domains cannot have CNAME records.
Question and response
Question
dig it-grad.ru. NS
Answer
it-grad.RU. 1 NS ens.mws.ru.
it-grad.RU. 1 NS ans.mws-mts.net.
it-grad.RU. 1 NS bns.mws.ru.
it-grad.RU. 1 NS cns.mws-mts.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0