mx.ouicken.com has no NS records.
NS records for this zone are defined at ouicken.com.
NS records for this zone are defined at ouicken.com.
Question and response
Question
dig mx.ouicken.com. NS
Answer
The response has no answer records.
Authority
ouicken.com. 3600 SOA dns.ouicken.com. hostmaster.ouicken.com. 1963617271 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0