Apex domains cannot have CNAME records.
Question and response
Question
dig ioi.com.ua. NS
Answer
ioi.com.ua. 2 NS nsd4.srv53.com.
ioi.com.ua. 2 NS nsd4.srv53.net.
ioi.com.ua. 2 NS nsa1.srv53.net.
ioi.com.ua. 2 NS nsc1.srv53.com.
ioi.com.ua. 2 NS nsb4.srv53.org.
ioi.com.ua. 2 NS nsd4.srv53.org.
ioi.com.ua. 2 NS nsa4.srv53.com.
ioi.com.ua. 2 NS nsb3.srv53.com.
ioi.com.ua. 2 NS nsc4.srv53.net.
ioi.com.ua. 2 NS nsc4.srv53.org.
ioi.com.ua. 2 NS nsb4.srv53.net.
ioi.com.ua. 2 NS nsa3.srv53.org.
Authority
The response has no authority records.
Additional
nsb4.srv53.net. 1 A 135.181.9.157
nsb4.srv53.org. 1 A 135.181.9.158
nsc4.srv53.net. 1 A 78.27.225.63
nsb4.srv53.net. 1 AAAA 2a01:4f9:4a:530c:181:9:157:2
nsb4.srv53.org. 1 AAAA 2a01:4f9:4a:530c:181:9:158:2
nsc4.srv53.net. 1 AAAA 2a02:2279:0:1201:78:27:225:63
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0