Apex domains cannot have CNAME records.
Question and response
Question
dig mijndnsserver.net. NS
Answer
mijndnsserver.net. 5 NS ns3.mijndnsserver.eu.
mijndnsserver.net. 5 NS ns2.mijndnsserver.nl.
mijndnsserver.net. 5 NS ns1.mijndnsserver.nl.
mijndnsserver.net. 5 NS ns4.mijndnsserver.net.
Authority
The response has no authority records.
Additional
ns1.mijndnsserver.nl. 5 A 37.48.84.96
ns2.mijndnsserver.nl. 5 A 185.84.140.163
ns3.mijndnsserver.eu. 5 A 89.149.219.85
ns4.mijndnsserver.net. 5 A 85.10.150.90
ns1.mijndnsserver.nl. 5 AAAA 2001:1af8:4700:a104:11:0:0:0
ns2.mijndnsserver.nl. 5 AAAA 2001:7b8:60c:1:4:100:16e2:1
ns3.mijndnsserver.eu. 5 AAAA 2001:1af8:5300:a005:1:0:0:1
ns4.mijndnsserver.net. 5 AAAA 2a01:7c8:bb0e:1cf:5054:ff:fee8:a378
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0