Apex domains cannot have CNAME records.
Question and response
Question
dig root.nl. NS
Answer
root.nl. 5 NS ns.echelon.nl.
root.nl. 5 NS nsy.echelon.nu.
root.nl. 5 NS nsx.echelon.nl.
Authority
The response has no authority records.
Additional
ns.echelon.nl. 5 A 217.119.226.66
nsx.echelon.nl. 5 A 149.210.248.62
nsy.echelon.nu. 5 A 5.28.62.43
ns.echelon.nl. 5 AAAA 2a02:1398:0:8:0:0:0:66
nsx.echelon.nl. 5 AAAA 2a01:7c8:aaca:21e:0:0:0:62
nsy.echelon.nu. 5 AAAA 2001:41c9:1:41c:0:0:0:43
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0