Apex domains cannot have CNAME records.
Question and response
Question
dig elteks.com.ua. NS
Answer
elteks.com.ua. 2 NS ns1.invest-it.com.ua.
elteks.com.ua. 2 NS ns2.invest-it.com.ua.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0