robotns2.second-ns.de has no CNAME records.
Question and response
Question
dig robotns2.second-ns.de. NS
Answer
The response has no answer records.
Authority
second-ns.de. 9739 SOA ns1.your-server.de. postmaster.your-server.de. 2025120200 86400 1800 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0