ns01.army.mil has no MX records.
Question and response
Question
dig ns01.army.mil. MX
Answer
The response has no answer records.
Authority
army.mil. 227 SOA ns01.army.mil. usarmy\.huachuca\.netcom\.mesg\.epdns-global.army.mil. 2012138579 900 90 2419200 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0