mx10.hostplan.nl has no CNAME records.
Question and response
Question
dig mx10.hostplan.nl. NS
Answer
The response has no answer records.
Authority
hostplan.nl. 471 SOA ns1.tiscomhosting.nl. hostmaster.tiscomhosting.nl. 2026012302 28800 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0