mail.pibit.ch has no CNAME records.
Question and response
Question
dig mail.pibit.ch. NS
Answer
The response has no answer records.
Authority
pibit.ch. 10800 SOA ns1.pibit.ch. dns.pibit.ch. 2026013101 10800 1800 604800 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0