Apex domains cannot have CNAME records.
Question and response
Question
dig kiewel-online.ch. NS
Answer
kiewel-online.ch. 5 NS ns-1642.awsdns-13.co.uk.
kiewel-online.ch. 5 NS ns-472.awsdns-59.com.
kiewel-online.ch. 5 NS ns-844.awsdns-41.net.
kiewel-online.ch. 5 NS ns-1389.awsdns-45.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0