a-dns-service.de has no CNAME records.
Question and response
Question
dig a-dns-service.de. NS
Answer
The response has no answer records.
Authority
de. 127 SOA f.nic.de. dns-operations.denic.de. 1772821994 7200 7200 3600000 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0