Apex domains cannot have CNAME records.
Question and response
Question
dig aktienprofi.com. NS
Answer
aktienprofi.com. 5 NS ns2.aktienprofi.com.
aktienprofi.com. 5 NS ns1.aktienprofi.com.
Authority
The response has no authority records.
Additional
ns1.aktienprofi.com. 5 A 2.59.170.203
ns2.aktienprofi.com. 5 A 2.59.170.207
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0