Apex domains cannot have CNAME records.
Question and response
Question
dig schweizer-internet.com. NS
Answer
schweizer-internet.com. 1 NS ns1.schweizer-internet.com.
schweizer-internet.com. 1 NS ns2.schweizer-internet.com.
Authority
The response has no authority records.
Additional
ns1.schweizer-internet.com. 1 A 89.39.149.195
ns2.schweizer-internet.com. 1 A 23.231.64.39
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0