In vSphere, what does the feature 'High Availability' do?

The feature 'High Availability' in vSphere is designed to minimize downtime for virtual machines by automatically restarting them on alternate hosts if there is a host failure. This capability is especially crucial in environments where uptime is critical, as it allows workloads to continue running with minimal disruption. When a host goes down, the High Availability system detects the failure and initiates the process of migrating the affected virtual machines to other functioning hosts within the cluster. This automatic recovery process ensures that services remain available and helps to achieve higher levels of availability for applications running within the virtual machines.

The other options touch on different aspects of virtualization and management but do not pertain to the specific functionality of High Availability. For instance, increasing network bandwidth relates to networking features rather than host-level failover. Creating backups of VMs is associated with data protection solutions, not with High Availability. Similarly, restricting access to VMs is related to security and permissions management within vSphere, distinct from ensuring availability.