Apex domains cannot have CNAME records.
Question and response
Question
dig derschwalbenkoenig.com. NS
Answer
derschwalbenkoenig.com. 5 NS ns16.domaincontrol.com.
derschwalbenkoenig.com. 5 NS ns15.domaincontrol.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0