Apex domains cannot have CNAME records.
Question and response
Question
dig interconnect.nl. NS
Answer
interconnect.nl. 5 NS nsauth3.interconnect-dns.be.
interconnect.nl. 5 NS nsauth1.interconnect-dns.nl.
interconnect.nl. 5 NS nsauth2.interconnect-dns.eu.
Authority
The response has no authority records.
Additional
nsauth1.interconnect-dns.nl. 5 A 212.83.192.198
nsauth2.interconnect-dns.eu. 5 A 213.207.64.198
nsauth3.interconnect-dns.be. 5 A 212.83.206.198
nsauth1.interconnect-dns.nl. 5 AAAA 2001:4018:1:192:0:0:0:198
nsauth2.interconnect-dns.eu. 5 AAAA 2001:4018:1:64:0:0:0:198
nsauth3.interconnect-dns.be. 5 AAAA 2001:4018:3:12:0:0:0:198
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0