Apex domains cannot have CNAME records.
Question and response
Question
dig digistatecloud.nl. NS
Answer
digistatecloud.nl. 5 NS ns1.digistate.eu.
digistatecloud.nl. 5 NS ns3.digistate.org.
digistatecloud.nl. 5 NS ns2.digistate.nl.
Authority
The response has no authority records.
Additional
ns1.digistate.eu. 5 A 185.40.58.178
ns2.digistate.nl. 5 A 193.27.87.5
ns3.digistate.org. 5 A 46.19.34.229
ns1.digistate.eu. 5 AAAA 2a01:4d60:3:1:3:0:0:1
ns2.digistate.nl. 5 AAAA 2a01:4d60:1:87:0:0:0:5
ns3.digistate.org. 5 AAAA 2a02:2770:0:0:21a:4aff:fe5c:2cd0
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0