Which vSphere feature protects against host hardware failures by restarting virtual machines on hosts that are running in the cluster?

The feature that protects against host hardware failures by restarting virtual machines on other operational hosts within a cluster is vSphere High Availability (HA). vSphere HA is designed to monitor the availability of hosts in a cluster and automatically restart virtual machines that were running on a failed host. When a hardware failure occurs in a host, vSphere HA detects this failure and initiates a failover process, which involves restarting the affected VMs on other healthy hosts within the cluster. This ensures minimal downtime and maximizes application availability.

While vSphere vMotion allows the live migration of virtual machines from one host to another without downtime, it does not specifically address hardware failures. vSphere Fault Tolerance provides continuous availability by creating a live shadow instance of a VM running on another host, but it is not primarily about restarting VMs after a failure. vSphere Distributed Resource Scheduler (DRS) is focused on resource allocation and load balancing across hosts in a cluster but does not handle host failures in the same manner as HA does.

In summary, vSphere HA is the correct answer as it directly relates to protecting virtual machines against hardware failures through automated restarts on operational hosts within the cluster.