ns2.backbone.ch has no CNAME records.
Question and response
Question
dig ns2.backbone.ch. NS
Answer
The response has no answer records.
Authority
backbone.ch. 9751 SOA ns1.backbone.ch. hostmaster.backbone.ch. 2025112601 600 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0