Apex domains cannot have CNAME records.
Question and response
Question
dig static.cablecom.ch. NS
Answer
static.cablecom.ch. 5 NS ns2.cablecom.net.
static.cablecom.ch. 5 NS ns1.cablecom.net.
Authority
The response has no authority records.
Additional
ns1.cablecom.net. 5 A 195.34.133.133
ns2.cablecom.net. 5 A 213.47.222.133
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0