Apex domains cannot have CNAME records.
Question and response
Question
dig sunic.ua. NS
Answer
sunic.ua. 5 NS ns.secondary.net.ua.
sunic.ua. 5 NS ns.sunic.ua.
Authority
The response has no authority records.
Additional
ns.sunic.ua. 5 A 167.172.42.154
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0