_netblocks.ipnet.ua has no CNAME records.
Question and response
Question
dig _netblocks.ipnet.ua. NS
Answer
The response has no answer records.
Authority
ipnet.ua. 10081 SOA ns1.ip.net.ua. hostmaster.ip.net.ua. 2026022300 14400 3600 1209600 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0