Apex domains cannot have CNAME records.
Question and response
Question
dig ostendis.ch. NS
Answer
ostendis.ch. 5 NS ch.ch-inter.net.
ostendis.ch. 5 NS nl.ch-inter.net.
ostendis.ch. 5 NS de.ch-inter.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0