Failover is the automatic switching to a standby system when a primary component fails or becomes unavailable. The defining characteristic is automation — failover happens without human intervention, which separates it from manual switchover procedures. For mission-critical systems, the time between failure and failover is measured in seconds or milliseconds.
Failover requires redundant infrastructure configured to detect failure and assume primary responsibilities immediately. Database clusters, load-balanced web server farms, redundant network connections, and cloud availability zones all implement failover at different layers.
CISSP Relevance
Failover is addressed in Domain 7 (Security Operations) within availability and business continuity concepts. CISSP candidates must understand failover in the context of high availability system design and how failover testing connects to recovery planning validation.
External reference: NIST SP 800-34 Contingency Planning Guide
Related terms: Disaster Recovery, Recovery Time Objective