Apex domains cannot have CNAME records.
Question and response
Question
dig agn-technical.nl. NS
Answer
agn-technical.nl. 5 NS ns3.cyso.net.
agn-technical.nl. 5 NS ns2.cyso.eu.
agn-technical.nl. 5 NS ns1.cyso.nl.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0