mailforward31.cloudns.net has no CNAME records.
Question and response
Question
dig mailforward31.cloudns.net. NS
Answer
The response has no answer records.
Authority
cloudns.net. 5361 SOA pns1.cloudns.net. support.cloudns.net. 2026021702 7200 3600 1209600 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0