mx.dukeredcross.com has no NS records.
NS records for this zone are defined at dukeredcross.com.
NS records for this zone are defined at dukeredcross.com.
Question and response
Question
dig mx.dukeredcross.com. NS
Answer
The response has no answer records.
Authority
dukeredcross.com. 3600 SOA dns.dukeredcross.com. hostmaster.dukeredcross.com. 1604413720 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0