An engineer configures the wireless LAN controller to perform 802.1x user authentication. Which option must be enabled to ensure that client devices can connect to the wireless, even when WLC cannot…

Local EAP is a feature on the Cisco WLC that processes EAP authentication requests locally using a local user database or an embedded LDAP backend, acting as a fallback when the configured RADIUS server is unavailable - it handles the full EAP exchange on the controller without requiring an external AAA server.

Cisco Centralized Key Management (CCKM) is a fast-roaming technology that allows clients to re-associate to new APs without a full re-authentication, but it does not provide authentication when RADIUS is unreachable.

Authentication caching (also called RADIUS authentication caching) can cache previously authenticated credentials for a period, but it is not the primary mechanism designed to provide full EAP authentication locally when RADIUS is down.

Pre-authentication is a concept associated with 802.11r fast BSS transition or proactive key caching before roaming, and it does not address the scenario of RADIUS server unavailability.