mx.yewpingchin.com has no NS records.
NS records for this zone are defined at yewpingchin.com.
NS records for this zone are defined at yewpingchin.com.
Question and response
Question
dig mx.yewpingchin.com. NS
Answer
The response has no answer records.
Authority
yewpingchin.com. 3600 SOA dns.yewpingchin.com. hostmaster.yewpingchin.com. 1499114065 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0