mx1.support.nl has no CNAME records.
Question and response
Question
dig mx1.support.nl. NS
Answer
The response has no answer records.
Authority
support.nl. 6218 SOA ns3.infracom.nl. dom-reg.infracom.nl. 2024092601 21600 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0