mx1.data-hotel.net has no CNAME records.
Question and response
Question
dig mx1.data-hotel.net. NS
Answer
The response has no answer records.
Authority
data-hotel.net. 3270 SOA zns01.data-hotel.net. hostmaster.data-hotel.net. 2026022401 1800 600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0