mx4.ipasrv.us has no CNAME records.
Question and response
Question
dig mx4.ipasrv.us. NS
Answer
The response has no answer records.
Authority
ipasrv.us. 9895 SOA dns.ipasrv.us. dns-admin.ipasrv.us. 2026010182 10800 3600 1209600 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0