Apex domains cannot have CNAME records.
Question and response
Question
dig ezorg.nl. NS
Answer
ezorg.nl. 2 NS ns02.ezorg.nl.
ezorg.nl. 2 NS ns03.ezorg.nl.
ezorg.nl. 2 NS ns01.ezorg.nl.
Authority
The response has no authority records.
Additional
ns01.ezorg.nl. 2 A 37.9.216.40
ns02.ezorg.nl. 2 A 23.88.72.142
ns03.ezorg.nl. 2 A 90.145.213.161
ns02.ezorg.nl. 2 AAAA 2a01:4f8:272:5d1c:0:0:0:53
ns03.ezorg.nl. 2 AAAA 2a02:120:404b:1000:0:0:3:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0