mx3.braintrust.at has no CNAME records.
Question and response
Question
dig mx3.braintrust.at. NS
Answer
The response has no answer records.
Authority
braintrust.at. 742 SOA dns1.braintrust.at. hostmaster.braintrust.at. 2023102401 600 300 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0