Apex domains cannot have CNAME records.
Question and response
Question
dig eunic.net.ua. NS
Answer
eunic.net.ua. 5 NS ns.kh.ua.
eunic.net.ua. 5 NS ns.zp.ua.
eunic.net.ua. 5 NS ns.dn.ua.
eunic.net.ua. 5 NS ns.sm.ua.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0