mx101.solcon.nl has no CNAME records.
Question and response
Question
dig mx101.solcon.nl. NS
Answer
The response has no answer records.
Authority
solcon.nl. 2049 SOA nsauth01.solcon.nl. postmaster.solcon.nl. 2026024730 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0