Apex domains cannot have CNAME records.
Question and response
Question
dig webmad.de. NS
Answer
webmad.de. 4 NS ns-a1.webmad.de.
webmad.de. 4 NS ns-a2.webmad.de.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0