ns4.dnsv2.com has no CNAME records.
Question and response
Question
dig ns4.dnsv2.com. NS
Answer
The response has no answer records.
Authority
dnsv2.com. 180 SOA ns3.dnsv2.com. level3dnsadmin.dnspod.com. 1764904776 3600 180 1209600 180
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0