Apex domains cannot have CNAME records.
Question and response
Question
dig infracom.nl. NS
Answer
infracom.nl. 5 NS ns3.infracom.nl.
infracom.nl. 5 NS ns7.infracom.nl.
infracom.nl. 5 NS ns5.infracom.nl.
Authority
The response has no authority records.
Additional
ns3.infracom.nl. 5 A 94.247.73.3
ns5.infracom.nl. 5 A 94.247.75.5
ns7.infracom.nl. 5 A 89.146.18.7
ns3.infracom.nl. 5 AAAA 2a02:ca0:2:0:0:0:0:3
ns5.infracom.nl. 5 AAAA 2a02:ca0:1:0:0:0:0:5
ns7.infracom.nl. 5 AAAA 2a02:22a0:bbb6:300:77:0:0:7
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0