mxdefr01.proinity.net has no CNAME records.
Question and response
Question
dig mxdefr01.proinity.net. NS
Answer
The response has no answer records.
Authority
proinity.net. 4581 SOA ns-1944.awsdns-51.co.uk. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0