Apex domains cannot have CNAME records.
Question and response
Question
dig druckerzubehoer.de. NS
Answer
druckerzubehoer.de. 2 NS adel.ns.cloudflare.com.
druckerzubehoer.de. 2 NS rustam.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0