HA
High Availability
Designing systems for minimal downtime through redundancy and failover.
High availability keeps services reachable despite component failure by combining redundancy, clustering, load balancing, and automatic failover to remove single points of failure. It is usually expressed as a percentage of uptime, where each added nine sharply shrinks tolerable annual downtime. It supports the availability leg of the CIA triad and underpins disaster recovery and business continuity planning. A pitfall is conflating it with fault tolerance: fault tolerance aims for no interruption at all, while high availability accepts brief, automatic recovery.
Looking HA up is step one. Getting tested on it is step two.
A free account opens all 4 Domain 1 objectives, 271 exam-style questions with a lesson and a lab on each, a placement check that skips what you already know, and a dated plan. No card.
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