Apex domains cannot have CNAME records.
Question and response
Question
dig myrasec.de. NS
Answer
myrasec.de. 5 NS a.myradns.de.
myrasec.de. 5 NS c.myradns.de.
myrasec.de. 5 NS b.myradns.de.
Authority
The response has no authority records.
Additional
a.myradns.de. 5 A 185.5.81.1
b.myradns.de. 5 A 185.5.81.2
c.myradns.de. 5 A 91.236.122.129
a.myradns.de. 5 AAAA 2a02:cb40:0:0:0:0:0:1
b.myradns.de. 5 AAAA 2a02:cb40:100:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0