mx71.mx71.net has no CNAME records.
Question and response
Question
dig mx71.mx71.net. NS
Answer
The response has no answer records.
Authority
mx71.net. 64142 SOA ns1.ns71.net. domadm.ketele.at. 2026020302 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0