Apex domains cannot have CNAME records.
Question and response
Question
dig everest.vn.ua. NS
Answer
everest.vn.ua. 4 NS ns2.enet.vn.ua.
everest.vn.ua. 4 NS ns1.enet.vn.ua.
everest.vn.ua. 4 NS ns3.enet.vn.ua.
Authority
The response has no authority records.
Additional
ns1.enet.vn.ua. 5 A 217.30.200.1
ns2.enet.vn.ua. 5 A 217.30.200.2
ns3.enet.vn.ua. 5 A 193.243.158.14
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0