An administrator must choose between deploying a virtual witness or a physical witness for a...

The correct answer is C, reduced vSphere licensing. This is because using a virtual witness appliance instead of a physical witness host can save on vSphere licensing costs, as the virtual witness appliance does not consume a vSphere license. The virtual witness appliance is a preconfigured virtual machine that runs ESXi and is distributed as an OVA file. It can be deployed on any ESXi host that has network connectivity to both data sites of the stretched cluster. The virtual witness appliance does not run any virtual machines other than itself and only hosts witness components of virtual machine objects. The other options are incorrect for the following reasons:

A, increased vSAN datastore capacity, is incorrect because using a virtual witness appliance does not affect the vSAN datastore capacity. The witness appliance does not store any customer data, only metadata, such as the size and UUID of vSAN object and components. The witness appliance also does not contribute any storage devices to the vSAN datastore.

B, shared metadata between separate clusters, is incorrect because using a virtual witness appliance does not enable sharing metadata between separate clusters. The witness appliance is dedicated to one stretched cluster and cannot serve as a witness for multiple clusters. The witness appliance maintains consistency between the two data sites of the stretched cluster by hosting witness components that act as tie-breakers in case of a site failure or network partition.

D, additional compute capacity for running VMs, is incorrect because using a virtual witness appliance does not provide additional compute capacity for running VMs. The witness appliance does not run any VMs other than itself and does not participate in any compute operations of the stretched cluster. The witness appliance only hosts witness components that consume minimal CPU and memory resources. References:

VMware vSAN Specialist v2 Exam Preparation Guide, page 11

Deploying a vSAN Witness Appliance