What does a Multi-AZ pattern involve?

A Multi-AZ pattern involves deploying instances across multiple Availability Zones within a region to enhance the availability and fault tolerance of applications. In this configuration, at least two instances are set up in separate Availability Zones which are connected through a load balancer. This setup ensures that if one Availability Zone experiences an outage, the other zone can continue to function normally, thereby preventing downtime and maintaining service availability.

Using load balancing, traffic can be distributed amongst these instances, offering better resource utilization and performance. This architecture is particularly crucial for applications that require high availability and cannot afford to go offline due to localized issues. The load balancer also helps manage failover automatically, directing traffic only to healthy instances.

In contrast, deploying multiple servers within a single Availability Zone or considering configurations with only a single instance do not provide this level of redundancy and resilience. Similarly, features that focus solely on auto-scaling do not inherently imply a Multi-AZ setup, as they may or may not involve cross-zone deployment.