High Availability
Designing systems to stay operational with minimal downtime even when components fail.
High availability (HA) is an architectural goal that keeps systems running by eliminating single points of failure through redundancy and automatic failover. On AWS, distributing resources across multiple Availability Zones within a Region is the standard approach: if one data center fails, traffic shifts to healthy zones automatically via services like Elastic Load Balancing. The critical CLF-C02 distinction is between high availability and fault tolerance. Fault tolerance means zero downtime and zero data loss through fully redundant parallel systems, while high availability accepts a brief recovery window. Questions hinting at “minimal downtime” or “automatic recovery” describe HA; questions requiring absolutely no disruption describe fault tolerance.
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