Apex domains cannot have CNAME records.
Question and response
Question
dig chello.nl. NS
Answer
chello.nl. 5 NS ns2.upc.biz.
chello.nl. 5 NS ns1.upc.biz.
chello.nl. 5 NS ns3.upc.biz.
Authority
The response has no authority records.
Additional
ns1.upc.biz. 5 A 195.34.133.133
ns2.upc.biz. 5 A 213.47.222.133
ns3.upc.biz. 5 A 195.20.106.133
ns1.upc.biz. 5 AAAA 2001:730:3e12:0:0:0:0:133
ns2.upc.biz. 5 AAAA 2001:730:3e12:1000:0:0:0:133
ns3.upc.biz. 5 AAAA 2001:678:2e4:0:0:0:0:133
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0