Apex domains cannot have CNAME records.
Question and response
Question
dig coordinator.ua. NS
Answer
coordinator.ua. 4 NS ns.net.ua.
coordinator.ua. 4 NS ns.zp.ua.
coordinator.ua. 4 NS ns.kh.ua.
coordinator.ua. 4 NS ns.sm.ua.
coordinator.ua. 4 NS ns.dn.ua.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0