What is the difference between active-passive and active-active HA in FortiGate?

The distinction between active-passive and active-active High Availability (HA) configurations in FortiGate revolves around how traffic is managed and the role of each unit within the HA cluster.

In an active-passive HA setup, there is one primary unit that actively handles all traffic, while a secondary unit remains on standby. The backup unit is not involved in processing traffic during normal operations but is ready to take over immediately if the primary unit experiences a failure. This ensures continuity of service by providing redundancy but does not utilize the capabilities of the secondary unit during regular operations.

In contrast, active-active HA allows both units to simultaneously process traffic, distributing the load between them. This configuration not only enhances performance by using the resources of each unit but also improves overall system reliability. If one unit fails, the other can continue to operate without service interruption, but there is a need for proper load balancing mechanisms to ensure that traffic is appropriately shared between the active units.

The other options do not correctly represent the fundamental characteristics of these HA configurations. For instance, while it is true that active-active configurations typically require more robust hardware to manage the simultaneous traffic loads from multiple units, this is not the defining difference. Reliability is a crucial factor in both setups but can vary based