What is one way to increase the availability of an application hosted on AWS?

Deploying an application across multiple Availability Zones significantly enhances its availability. Availability Zones are distinct locations within a region designed to be isolated from failures in other Availability Zones. By distributing application resources, such as compute instances, across multiple zones, you reduce the risk of downtime due to localized events, such as power outages or hardware failures. This redundancy ensures that if one zone becomes unavailable, the other zones can continue to serve the application, providing a seamless experience for users.

Scaling using a single powerful EC2 instance, limiting access to a select group of users, or relying on on-premises storage solutions do not contribute to increasing an application’s availability. A single EC2 instance presents a single point of failure. Limiting access can enhance security but does not impact the application's operational availability. On-premises solutions also do not benefit from the geographical redundancy and resilience that cloud infrastructure offers. Therefore, deploying applications across multiple Availability Zones is the most effective way to ensure high availability on AWS.