mx.v.mailcloud.com.cn has no NS records.
NS records for this zone are defined at mailcloud.com.cn.
NS records for this zone are defined at mailcloud.com.cn.
Question and response
Question
dig mx.v.mailcloud.com.cn. NS
Answer
The response has no answer records.
Authority
mailcloud.com.cn. 180 SOA ns3.dnsv2.com. level3dnsadmin.dnspod.com. 1758182851 3600 180 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0