A customer wishes to increase the availability of their AWS Cloud hosted application. What is the recommended approach?

Hosting application instances in multiple Availability Zones is a well-established best practice for increasing the availability of applications within AWS. Each Availability Zone operates independently, with its own power, cooling, and physical security, ensuring that if one zone experiences an outage, the others can continue to function. By distributing application instances across several zones, the application can maintain functionality and performance even in the event of an issue affecting one zone. This configuration supports resilience and fault tolerance, critical aspects of high availability for cloud-based applications.

Leveraging multiple Availability Zones allows for load balancing, redundancy, and improved scalability, which collectively contribute to a more reliable service for end users. In contrast, focusing on a single edge location or limiting the application to one region would create points of failure that can drastically reduce availability. Reducing the number of instances may cut costs but compromises the overall redundancy and scalability needed for high availability. Thus, hosting application instances across multiple Availability Zones is the most effective strategy to enhance availability.