Apex domains cannot have CNAME records.
Question and response
Question
dig noris.de. NS
Answer
noris.de. 5 NS dns.noris.ch.
noris.de. 5 NS dns.noris.de.
noris.de. 5 NS dns.noris.net.
Authority
The response has no authority records.
Additional
dns.noris.de. 5 A 192.109.102.65
dns.noris.net. 5 A 213.95.0.65
dns.noris.de. 5 AAAA 2001:780:53d2:0:0:0:0:53
dns.noris.net. 5 AAAA 2001:780:53d1:0:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0