Apex domains cannot have CNAME records.
Question and response
Question
dig dhub.ru. NS
Answer
dhub.ru. 5 NS ns4.dhub.ru.
dhub.ru. 5 NS ns3.dhub.ru.
Authority
The response has no authority records.
Additional
ns3.dhub.ru. 5 A 188.127.232.28
ns4.dhub.ru. 5 A 188.127.233.13
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0