Apex domains cannot have CNAME records.
Question and response
Question
dig gigacloud.ua. NS
Answer
gigacloud.ua. 5 NS ns4.gigacloud.ua.
gigacloud.ua. 5 NS ns2.gigacloud.ua.
gigacloud.ua. 5 NS ns1.gigacloud.ua.
gigacloud.ua. 5 NS ns3.gigacloud.ua.
Authority
The response has no authority records.
Additional
ns1.gigacloud.ua. 5 A 94.131.247.20
ns2.gigacloud.ua. 5 A 195.238.187.235
ns3.gigacloud.ua. 5 A 185.250.21.49
ns4.gigacloud.ua. 5 A 94.131.243.6
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0