Which feature allows a device to remain operational when the remote authentication server is unreachable?

Which feature allows a device to remain operational when the remote authentication server is unreachable?

• A. MAC caching
• B. MAC Authentication
• C. Authentication survivability
• D. Opportunistic key caching

Answer: (C)

The idea being tested is how a network can stay usable even when the central authentication server can’t be reached. Authentication survivability provides a fail-open path so devices can continue to operate during an AAA outage. In practice, when the RADIUS/AAA server is unreachable, switches or wireless controllers can allow access to a limited, predefined set of services based on cached credentials or local policies, keeping users connected long enough to restore authentication. This avoids a complete outage while you bring the authentication infrastructure back online. MAC caching and MAC authentication are different approaches that deal with how devices are authenticated or re-authenticated, but they don’t specifically address maintaining operation during an AAA server outage. Opportunistic key caching is related to speeding up wireless key exchanges, not to sustaining access when the remote auth server is down.

The idea being tested is how a network can stay usable even when the central authentication server can’t be reached. Authentication survivability provides a fail-open path so devices can continue to operate during an AAA outage. In practice, when the RADIUS/AAA server is unreachable, switches or wireless controllers can allow access to a limited, predefined set of services based on cached credentials or local policies, keeping users connected long enough to restore authentication. This avoids a complete outage while you bring the authentication infrastructure back online.

MAC caching and MAC authentication are different approaches that deal with how devices are authenticated or re-authenticated, but they don’t specifically address maintaining operation during an AAA server outage. Opportunistic key caching is related to speeding up wireless key exchanges, not to sustaining access when the remote auth server is down.