A fallback page is a simplified backup web page that stays accessible when the main service is down, overloaded, or being protected by security controls. It usually contains only essential information, such as service status, basic instructions, or contact details, so it can load quickly and rely on fewer dependencies.
In cyber security, fallback pages help preserve availability during incidents like distributed denial-of-service attacks, maintenance windows, or upstream outages. If the primary portal is unreachable, users can still see whether the service is affected and what to do next. Defenders use them to reduce confusion, support incident response, and prevent total loss of communication even when traffic filtering, rate limiting, or rerouting is underway.