Apex domains cannot have CNAME records.
Question and response
Question
dig visp.com.ua. NS
Answer
visp.com.ua. 5 NS ns1.visp.com.ua.
visp.com.ua. 5 NS ns.secondary.net.ua.
visp.com.ua. 5 NS ns2.visp.com.ua.
Authority
The response has no authority records.
Additional
ns1.visp.com.ua. 5 A 91.217.61.132
ns2.visp.com.ua. 5 A 91.217.61.133
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0