Apex domains cannot have CNAME records.
Question and response
Question
dig hypergrid.nl. NS
Answer
hypergrid.nl. 4 NS ns3.kpn.net.
hypergrid.nl. 4 NS ns02.is.nl.
hypergrid.nl. 4 NS ns01.is.nl.
hypergrid.nl. 4 NS ns13.kpn.net.
hypergrid.nl. 4 NS ns03.is.nl.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0