sid.f5s.de has no CNAME records.
Question and response
Question
dig sid.f5s.de. NS
Answer
The response has no answer records.
Authority
f5s.de. 1323 SOA ns.inwx.de. hostmaster.fuchsi.de. 2026011700 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0