What is the backup operational mode that automatically switches to a standby system when the primary fails?

• A. Failover
• B. Failback
• C. Redundancy
• D. Backup

Answer: (A)

Failover is the automatic switch to a standby system when the primary fails. In high-availability setups, a monitor or heartbeat detects that the active component is down, and the standby is promoted to take over, often with little or no downtime. This is why it best fits the description of an operation mode that automatically switches to a standby when the primary fails. Once the primary is restored, you may perform a failback to return operations to it. The other terms describe related ideas but not the automatic switch: failback is the process of returning to the original primary after recovery, redundancy is having duplicate components for reliability, and backup refers to copying data for recovery rather than enabling live switching.