Apex domains cannot have CNAME records.
Question and response
Question
dig DHUB.RU. NS
Answer
DHUB.RU. 5 NS ns3.DHUB.RU.
DHUB.RU. 5 NS ns4.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