Apex domains cannot have CNAME records.
Question and response
Question
dig dertouragent.com.ua. NS
Answer
dertouragent.com.ua. 5 NS ns3.hostpro.ua.
dertouragent.com.ua. 5 NS ns1.hostpro.ua.
dertouragent.com.ua. 5 NS ns2.hostpro.ua.
dertouragent.com.ua. 5 NS ns4.hostpro.ua.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0