Apex domains cannot have CNAME records.
Question and response
Question
dig CITYTELECOM.RU. NS
Answer
CITYTELECOM.RU. 3 NS ns10.hoster.RU.
CITYTELECOM.RU. 3 NS ns11.hoster.RU.
Authority
The response has no authority records.
Additional
ns10.hoster.ru. 3 A 195.128.50.221
ns11.hoster.ru. 3 A 31.28.20.108
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0