Apex domains cannot have CNAME records.
Question and response
Question
dig dn.ua. NS
Answer
dn.ua. 5 NS ho1.eunic.net.ua.
dn.ua. 5 NS ns.net.ua.
dn.ua. 5 NS ns.zp.ua.
dn.ua. 5 NS nn.ns.ua.
dn.ua. 5 NS ns.sm.ua.
dn.ua. 5 NS ns.kh.ua.
Authority
The response has no authority records.
Additional
nn.ns.ua. 172345 A 194.58.197.4
nn.ns.ua. 172345 AAAA 2a01:3f1:c001:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0