Apex domains cannot have CNAME records.
Question and response
Question
dig kurs.dn.ua. NS
Answer
kurs.dn.ua. 5 NS ns24.inhostedns.net.
kurs.dn.ua. 5 NS ns34.inhostedns.org.
kurs.dn.ua. 5 NS ns14.inhostedns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0