Apex domains cannot have CNAME records.
Question and response
Question
dig alt255.nl. NS
Answer
alt255.nl. 5 NS ns3.alt255.nl.
alt255.nl. 5 NS ns2.alt255.nl.
alt255.nl. 5 NS ns1.alt255.nl.
Authority
The response has no authority records.
Additional
ns1.alt255.nl. 5 A 185.103.159.158
ns2.alt255.nl. 5 A 185.94.228.152
ns3.alt255.nl. 5 A 185.95.29.200
ns1.alt255.nl. 5 AAAA 2a00:f10:400:4:1c00:aff:fe00:169c
ns2.alt255.nl. 5 AAAA 2a05:1500:501:1:1c00:67ff:fe00:108
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0