Apex domains cannot have CNAME records.
Question and response
Question
dig systemec.nl. NS
Answer
systemec.nl. 5 NS ns3.systemec.nl.
systemec.nl. 5 NS ns4.systemec.nl.
systemec.nl. 5 NS ns.systemec.nl.
systemec.nl. 5 NS ns2.systemec.nl.
Authority
The response has no authority records.
Additional
ns.systemec.nl. 5 A 89.20.90.102
ns2.systemec.nl. 5 A 89.20.90.89
ns3.systemec.nl. 5 A 89.20.64.132
ns4.systemec.nl. 5 A 85.203.0.188
ns2.systemec.nl. 5 AAAA 2a02:2170:103:3:0:0:0:89
ns3.systemec.nl. 5 AAAA 2a02:2170:102:2:0:0:0:132
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0