Apex domains cannot have CNAME records.
Question and response
Question
dig hoststar.ch. NS
Answer
hoststar.ch. 4 NS ns1.hoststar.ch.
hoststar.ch. 4 NS ns2.hoststar.ch.
hoststar.ch. 4 NS ns2x.hoststar.ch.
Authority
The response has no authority records.
Additional
ns1.hoststar.ch. 4 A 213.133.109.162
ns2.hoststar.ch. 4 A 144.76.41.166
ns2x.hoststar.ch. 4 A 185.48.231.253
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0