Apex domains cannot have CNAME records.
Question and response
Question
dig pcx.yourfilter.nl. NS
Answer
pcx.yourfilter.nl. 5 NS ns093.auroradns.info.
pcx.yourfilter.nl. 5 NS ns092.auroradns.nl.
pcx.yourfilter.nl. 5 NS ns091.auroradns.eu.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0