Apex domains cannot have CNAME records.
Question and response
Question
dig domainfactory.de. NS
Answer
domainfactory.de. 2 NS ns.namespace4you.de.
domainfactory.de. 2 NS ns2.namespace4you.de.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0