Apex domains cannot have CNAME records.
Question and response
Question
dig datux.nl. NS
Answer
datux.nl. 5 NS ns3.spothost.nl.
datux.nl. 5 NS ns1.spothost.eu.
datux.nl. 5 NS ns2.spot.host.
Authority
The response has no authority records.
Additional
ns1.spothost.eu. 5 A 185.58.57.1
ns2.spot.host. 5 A 94.237.90.65
ns1.spothost.eu. 5 AAAA 2a01:310:8312:1046:185:58:57:1
ns2.spot.host. 5 AAAA 2a04:3542:1000:910:e0c3:50ff:feec:7ce7
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0