Which protocol functions to provide a hot-standby processor during a failure?

The correct answer focuses on "SSO," which stands for Stateful Switchover. SSO is a high-availability feature used in Cisco networking devices that allows for a seamless transition of control between a primary and a standby processor. In the event of a failure of the primary processor, the standby processor can take over without losing any active sessions or requiring a complete reboot of the device. This is particularly important for maintaining uninterrupted service in critical network environments where downtime must be minimized.

SSO ensures that the state of the system is maintained and that traffic can continue flowing without disruption. When the primary processor fails, the SSO mechanism allows the backup processor to take over the responsibilities instantly and with minimal impact on performance.

Understanding SSO is crucial for network engineers as it relates directly to the design and implementation of high-availability networks, ensuring that essential services remain operational during hardware failures.