How is fault tolerance implemented in vSphere?

Fault tolerance in vSphere is implemented by providing continuous availability for virtual machines (VMs) through a process known as "live shadowing." This mechanism ensures that there is a secondary instance of the VM, known as a shadow VM, that runs in real-time and remains in perfect sync with the primary VM. If the primary VM experiences a failure, the shadow VM can immediately take over without any downtime or data loss, thus maintaining high availability for critical applications. This capability is particularly important in environments where uptime and data integrity are paramount.

The other options do not reflect the specific mechanism of fault tolerance in vSphere. Creating backups of VMs serves as a data recovery solution rather than continuous availability, while scheduling automatic restarts is more about recovering from failures rather than preventing them in real-time. Increasing the number of CPU cores assigned to VMs may enhance performance but does not directly relate to fault tolerance strategies. Hence, the continuous availability provided by the live shadow instance rightly characterizes how fault tolerance is achieved in VMware vSphere.