Apex domains cannot have CNAME records.
Question and response
Question
dig hostmaster.ua. NS
Answer
hostmaster.ua. 5 NS ns1.ns.ua.
hostmaster.ua. 5 NS bg.ns.ua.
hostmaster.ua. 5 NS ho1.ns.hostmaster.ua.
Authority
The response has no authority records.
Additional
bg.ns.ua. 171695 A 185.136.96.185
bg.ns.ua. 171695 A 185.136.97.185
ho1.ns.hostmaster.ua. 5 A 195.47.253.6
bg.ns.ua. 171695 AAAA 2a06:fb00:1:0:0:0:2:185
bg.ns.ua. 171695 AAAA 2a06:fb00:1:0:0:0:4:185
ho1.ns.hostmaster.ua. 5 AAAA 2001:67c:258:0:0:0:0:6
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0