Apex domains cannot have CNAME records.
Question and response
Question
dig databay.de. NS
Answer
databay.de. 5 NS ns.databay.de.
databay.de. 5 NS ns2.databay.de.
Authority
The response has no authority records.
Additional
ns.databay.de. 5 A 193.32.64.129
ns2.databay.de. 5 A 93.159.251.193
ns.databay.de. 5 AAAA 2001:67c:2054:2:0:0:0:81
ns2.databay.de. 5 AAAA 2a00:fe0:2:500:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0