Apex domains cannot have CNAME records.
Question and response
Question
dig opsx.nl. NS
Answer
opsx.nl. 5 NS ns03.etherned.nl.
opsx.nl. 5 NS ns04.etherned.nl.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0