What vSphere component provides continuous availability for mission-critical virtual machines?

The component that provides continuous availability for mission-critical virtual machines is vSphere Fault Tolerance. This feature allows a virtual machine to run in two instances simultaneously—one active and one passive. If the primary instance fails, the secondary instance takes over immediately without any loss of data or service interruption. This capability is particularly important for environments where uptime is critical, as it ensures that applications remain available even in the event of hardware or system faults.

In contrast, other options serve different purposes. vSphere vMotion allows for the live migration of virtual machines from one physical host to another without downtime, but it does not provide fault tolerance in terms of continuous availability. vSphere Replication offers a way to replicate virtual machines to another site for disaster recovery, enabling recovery after a failure, but it does not ensure immediate failover during a fault. vSphere HA (High Availability) aims to restart virtual machines on other hosts in the event of a host failure, but it typically involves a short downtime during the process of restarting the VM. Thus, for achieving true continuous availability, vSphere Fault Tolerance is the most appropriate solution.