Apex domains cannot have CNAME records.
Question and response
Question
dig unitel.net.ua. NS
Answer
unitel.net.ua. 4 NS nsb2.srv53.net.
unitel.net.ua. 4 NS nsc1.srv53.org.
unitel.net.ua. 4 NS nsa3.srv53.com.
unitel.net.ua. 4 NS nsc3.srv53.com.
unitel.net.ua. 4 NS nsa4.srv53.org.
unitel.net.ua. 4 NS nsb2.srv53.com.
unitel.net.ua. 4 NS nsd4.srv53.net.
unitel.net.ua. 4 NS nsd4.srv53.com.
unitel.net.ua. 4 NS nsd2.srv53.org.
unitel.net.ua. 4 NS nsc1.srv53.net.
unitel.net.ua. 4 NS nsb1.srv53.org.
unitel.net.ua. 4 NS nsa4.srv53.net.
Authority
The response has no authority records.
Additional
nsb1.srv53.org. 4 A 135.181.9.149
nsc1.srv53.net. 4 A 78.27.225.72
nsc1.srv53.org. 4 A 78.27.225.71
nsb1.srv53.org. 4 AAAA 2a01:4f9:4a:530c:181:9:149:2
nsc1.srv53.net. 4 AAAA 2a02:2279:0:1201:78:27:225:72
nsc1.srv53.org. 4 AAAA 2a02:2279:0:1201:78:27:225:71
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0