mx.propersupport.com has no NS records.
NS records for this zone are defined at propersupport.com.
NS records for this zone are defined at propersupport.com.
Question and response
Question
dig mx.propersupport.com. NS
Answer
The response has no answer records.
Authority
propersupport.com. 1800 SOA propersupport.com. root.propersupport.com. 1676297270 28800 7200 604800 86400
Additional
. 0 OPT ; payload 600, xrcode 0, version 0, flags 0