Apex domains cannot have CNAME records.
Question and response
Question
dig spectre-net.de. NS
Answer
spectre-net.de. 5 NS ns01.spectre-net.de.
spectre-net.de. 5 NS ns02.spectre-net.de.
Authority
The response has no authority records.
Additional
ns01.spectre-net.de. 5 A 217.197.91.176
ns02.spectre-net.de. 5 A 162.55.190.98
ns01.spectre-net.de. 5 AAAA 2a0a:4580:1023:0:0:0:0:1
ns02.spectre-net.de. 5 AAAA 2a01:4f8:1c1b:d4be:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0