mxfltr2.email-as.net has no CNAME records.
Question and response
Question
dig mxfltr2.email-as.net. NS
Answer
The response has no answer records.
Authority
email-as.net. 3600 SOA pdns1.provisiondata.net. hostmaster.ingconnect.net. 2023022002 1800 600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0