Apex domains cannot have CNAME records.
Question and response
Question
dig keyspecial.de. NS
Answer
keyspecial.de. 5 NS ns2.keyspecial.de.
keyspecial.de. 5 NS ns.keyspecial.de.
Authority
The response has no authority records.
Additional
ns.keyspecial.de. 5 A 62.141.48.100
ns2.keyspecial.de. 5 A 62.141.49.100
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0