rdns2.internetx.de has no CNAME records.
Question and response
Question
dig rdns2.internetx.de. NS
Answer
The response has no answer records.
Authority
internetx.de. 714 SOA nsa.domain-robot.org. support.internetx.com. 2025030500 43200 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0