Apex domains cannot have CNAME records.
Question and response
Question
dig mybb.de. NS
Answer
mybb.de. 5 NS arch.ns.cloudflare.com.
mybb.de. 5 NS riya.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0