auth3.artfiles.de has no CNAME records.
Question and response
Question
dig auth3.artfiles.de. NS
Answer
The response has no answer records.
Authority
artfiles.de. 114 SOA auth1.artfiles.de. hostmaster.artfiles.de. 2026030301 28800 14400 860400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0