A utility's FortiGate is configured to authenticate NOC staff against a RADIUS server first, with a local user group configured as a fallback. During a network outage, the RADIUS server becomes unreachable. What should happen for a NOC operator attempting to authenticate during the outage, assuming their account also exists locally?
Select an answer to reveal the explanation.
Short Explanation
Depending on one server for every login is asking for trouble the day that server has a bad afternoon. Configuring a local fallback means the FortiGate has a second place to check when RADIUS goes quiet, so the NOC doesn't grind to a halt because one box is unreachable. It's a deliberate safety net, not automatic magic — it only works because someone set it up in advance.
Full Explanation
FortiOS supports configuring multiple authentication sources in a defined order, so when a primary RADIUS server fails to respond, the FortiGate can be set up to fall back to checking a local user database (or another configured source) rather than failing the login outright — this is a deliberate resilience design, not a default that happens automatically without configuration. Claiming RADIUS unavailability always blocks authentication with no fallback ignores this configurable behavior and describes only what happens if no fallback source was set up. Silently granting access with no authentication check during an outage would be a serious security failure mode that FortiOS does not implement by design — availability problems on an authentication server are meant to trigger fallback to another verified source, never a bypass of verification entirely. There is also no mechanism that converts a RADIUS-based account to certificate-based authentication automatically during an outage; authentication method changes are administrative configuration choices, not automatic reactions to server unavailability. The operational caveat is that fallback only works if the local account already exists and its credentials are current — if the RADIUS-only workforce was never mirrored locally, there is nothing to fall back to. Confirm resilience by testing a login with the RADIUS server intentionally unreachable and verifying the local fallback account still authenticates.