Apex domains cannot have CNAME records.
Question and response
Question
dig rednet.ch. NS
Answer
rednet.ch. 4 NS customerdns003.redcloud.ch.
rednet.ch. 4 NS customerdns001.redcloud.ch.
rednet.ch. 4 NS customerdns002.redcloud.ch.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0