Apex domains cannot have CNAME records.
Question and response
Question
dig mx.org.ua. NS
Answer
mx.org.ua. 5 NS ns.itsupport.kiev.ua.
mx.org.ua. 5 NS ns2.itsupport.kiev.ua.
mx.org.ua. 5 NS ns.mx.org.ua.
Authority
The response has no authority records.
Additional
ns.mx.org.ua. 5 A 185.187.83.14
ns.itsupport.kiev.ua. 5 A 193.178.147.64
ns2.itsupport.kiev.ua. 5 A 185.187.81.20
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0