Reliability
A workload's ability to perform its function correctly and recover from failures.
Reliability is one of the six pillars of the AWS Well-Architected Framework and describes a system’s ability to perform its intended function correctly and consistently, including the capacity to automatically recover from infrastructure or service failures. AWS supports reliability through services such as Amazon Route 53 for DNS failover, Elastic Load Balancing to distribute traffic across healthy targets, and Auto Scaling to replace failed instances without manual intervention. The key exam distinction is between reliability and high availability: high availability minimizes downtime, while reliability is broader — not just staying up, but recovering correctly when something goes wrong. A highly available system that returns corrupted data is not reliable.
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