Apex domains cannot have CNAME records.
Question and response
Question
dig dorob.de. NS
Answer
dorob.de. 5 NS r3.dorob.de.
dorob.de. 5 NS r2.dorob.de.
dorob.de. 5 NS r5.dorob.de.
dorob.de. 5 NS r4.dorob.de.
dorob.de. 5 NS r1.dorob.de.
Authority
The response has no authority records.
Additional
r1.dorob.de. 5 A 89.36.33.25
r2.dorob.de. 5 A 185.121.133.107
r3.dorob.de. 5 A 84.252.123.120
r4.dorob.de. 5 A 185.144.70.155
r5.dorob.de. 5 A 5.132.162.171
r1.dorob.de. 5 AAAA 2a14:6780:1:0:0:0:0:a
r2.dorob.de. 5 AAAA 2a14:6780:0:0:0:0:0:107
r3.dorob.de. 5 AAAA 2a0c:2500:571:ffb:f935:ed9c:6751:df30
r4.dorob.de. 5 AAAA 2a0c:2502:0:f:798:189d:c2a3:572c
r5.dorob.de. 5 AAAA 2a03:3180:4001:104:0:0:1a9f:8250
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0