Apex domains cannot have CNAME records.
Question and response
Question
dig deltavastgoed.nl. NS
Answer
deltavastgoed.nl. 5 NS clarissa.ns.cloudflare.com.
deltavastgoed.nl. 5 NS joaquin.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0