Apex domains cannot have CNAME records.
Question and response
Question
dig scalera.ch. NS
Answer
scalera.ch. 5 NS dns2.scalera.ch.
scalera.ch. 5 NS dns1.scalera.ch.
Authority
The response has no authority records.
Additional
dns1.scalera.ch. 5 A 217.71.80.187
dns2.scalera.ch. 5 A 217.71.81.3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0