dns2.cdns.net has no MX records.
Question and response
Question
dig dns2.cdns.net. MX
Answer
The response has no answer records.
Authority
cdns.net. 3600 SOA dns1.cdns.net. admin.communitydns.net. 1771734876 900 400 3600000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0