Apex domains cannot have CNAME records.
Question and response
Question
dig burgwaelder.de. NS
Answer
burgwaelder.de. 5 NS ns1.sedoparking.com.
burgwaelder.de. 5 NS ns2.sedoparking.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0