Apex domains cannot have CNAME records.
Question and response
Question
dig vanoppen.com. NS
Answer
vanoppen.com. 5 NS ns-east.vanoppen.com.
vanoppen.com. 5 NS ns-west.vanoppen.com.
Authority
The response has no authority records.
Additional
ns-east.vanoppen.com. 5 A 172.104.14.170
ns-west.vanoppen.com. 5 A 168.245.136.140
ns-east.vanoppen.com. 5 AAAA 2600:3c03:0:0:f03c:91ff:fe3e:42f8
ns-west.vanoppen.com. 5 AAAA 2604:7fc0:0:0:0:0:0:140
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0