Apex domains cannot have CNAME records.
Question and response
Question
dig linknet.vn.ua. NS
Answer
linknet.vn.ua. 5 NS nsb2.srv53.com.
linknet.vn.ua. 5 NS nsb2.srv53.net.
linknet.vn.ua. 5 NS nsa4.srv53.net.
linknet.vn.ua. 5 NS nsd2.srv53.com.
linknet.vn.ua. 5 NS nsa1.srv53.org.
linknet.vn.ua. 5 NS nsb1.srv53.org.
linknet.vn.ua. 5 NS nsa3.srv53.com.
linknet.vn.ua. 5 NS nsc3.srv53.net.
linknet.vn.ua. 5 NS nsc3.srv53.org.
linknet.vn.ua. 5 NS nsc3.srv53.com.
linknet.vn.ua. 5 NS nsd1.srv53.net.
linknet.vn.ua. 5 NS nsd2.srv53.org.
Authority
The response has no authority records.
Additional
nsa1.srv53.org. 5 A 178.32.247.3
nsb1.srv53.org. 5 A 135.181.9.149
nsd1.srv53.net. 5 A 89.184.64.68
nsa1.srv53.org. 5 AAAA 2001:41d0:203:dee4:178:32:247:3
nsb1.srv53.org. 5 AAAA 2a01:4f9:4a:530c:181:9:149:2
nsd1.srv53.net. 5 AAAA 2a02:2278:70eb:298:89:184:64:68
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0