admission webhook "virtualmachine-validator.kubevirt.io" denied the request: spec.template.spec.hostname does not conform to the kubernetes DNS_LABEL rules : a lowercase RFC 1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name', or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?')

No. It's determined by Kubernetes.

Ok