Apex domains cannot have CNAME records.
Question and response
Question
dig inter-it.nl. NS
Answer
inter-it.nl. 5 NS ns.inter-it.nl.
inter-it.nl. 5 NS ns2.inter-it.nl.
inter-it.nl. 5 NS ns3.inter-it.nl.
Authority
The response has no authority records.
Additional
ns.inter-it.nl. 5 A 85.214.154.78
ns2.inter-it.nl. 5 A 85.214.150.179
ns3.inter-it.nl. 5 A 85.214.213.116
ns.inter-it.nl. 5 AAAA 2a01:238:435f:8600:a87e:aa5e:514b:59c9
ns2.inter-it.nl. 5 AAAA 2a01:238:4355:7800:2d09:68be:a4dc:ffc5
ns3.inter-it.nl. 5 AAAA 2a01:238:4316:6f00:9f73:49ec:a8a1:53a4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0