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