Apex domains cannot have CNAME records.
Question and response
Question
dig kontrabuss.org. NS
Answer
kontrabuss.org. 5 NS ns2.kontrabuss.org.
kontrabuss.org. 5 NS ns1.kontrabuss.org.
Authority
The response has no authority records.
Additional
ns1.kontrabuss.org. 5 A 51.68.197.226
ns2.kontrabuss.org. 5 A 51.195.180.4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0