1. True – At the time of writing, Istio can only be used in a Kubernetes environment, though integration with VMs is being planned.
2. False – The Istio sidecar can be enabled for new applications if the namespace is annotated with the istio-injection=enabled label. The sidecar can be enabled through the istioctl command.
3. True – Istio has more than 57 CRDs.
4. True – It is necessary to install CRDs to extend Kubernetes so that it can use Istio's features.
5. True – The existing application needs to be taken down first and then you need to enable sidecar proxy injection, either by annotating the namespace with a label or by using istioctl kube-inject to modify the existing application's manifest.
6. False – It is possible to disable the sidecar for a microservice by setting the pod annotation to sidecar.istio.io/inject: "false", even when a namespace has already been annotated with the istio-injection=enabled label.
7. False – Istio custom resources can be managed through the istioctl command, as well as through the kubectl command.