Answer: Across multiple Availability Zones

## Explanation To achieve high availability for an application hosted on Amazon EC2 instances, the instances should be deployed **across multiple Availability Zones (AZs)**. Here's why: ### Key Concepts: - **Availability Zones (AZs)**: - Each AZ is a physically separate data center within an AWS Region - AZs are designed to be isolated from failures in other AZs - Deploying across multiple AZs provides fault tolerance and high availability ### Why Multiple AZs Provide High Availability: 1. **Fault Isolation**: If one AZ experiences an outage, the application can continue running from other AZs 2. **Automatic Failover**: Load balancers can distribute traffic across instances in multiple AZs 3. **Redundancy**: Data and services are replicated across different physical locations ### Why Other Options Are Incorrect: - **Multiple Edge Locations**: Edge locations are for content delivery (CloudFront), not for hosting EC2 instances - **Multiple VPCs**: While VPCs provide network isolation, they don't inherently provide high availability across different physical locations - **Multiple AWS Accounts**: This is for organizational/security separation, not high availability ### Best Practice: For maximum availability, deploy EC2 instances across at least 2-3 Availability Zones and use an Elastic Load Balancer to distribute traffic evenly.

Author: Ritesh Yadav