Apex domains cannot have CNAME records.
Question and response
Question
dig vm.cyberlink.ch. NS
Answer
vm.cyberlink.ch. 4 NS ns3.cyberlink.ch.
vm.cyberlink.ch. 4 NS ns2.cyberlink.ch.
vm.cyberlink.ch. 4 NS ns1.cyberlink.ch.
Authority
The response has no authority records.
Additional
ns1.cyberlink.ch. 4 A 62.12.130.28
ns2.cyberlink.ch. 4 A 193.246.253.194
ns3.cyberlink.ch. 4 A 213.144.148.42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0