Apex domains cannot have CNAME records.
Question and response
Question
dig hostnet.nl. NS
Answer
hostnet.nl. 5 NS ns01.authdns.hostnet.nl.
hostnet.nl. 5 NS ns02.authdns.hostnet.nl.
Authority
The response has no authority records.
Additional
ns01.authdns.hostnet.nl. 5 A 195.206.121.11
ns02.authdns.hostnet.nl. 5 A 185.10.11.11
ns01.authdns.hostnet.nl. 5 AAAA 2001:67c:28cc:0:0:0:0:11
ns02.authdns.hostnet.nl. 5 AAAA 2001:67c:3c0:0:0:0:0:11
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0