Answer: Configure the application to use Multi-AZ EC2 Auto Scaling and create an Application Load Balancer

## Explanation The correct answer is **A** because: 1. **Current Architecture Issue**: The application currently uses EC2 instances in a **single Availability Zone**, which creates a single point of failure. If that AZ goes down, the application becomes unavailable even though the RDS database is already Multi-AZ. 2. **High Availability Requirements**: To achieve high availability for the application tier, we need: - **Multi-AZ deployment**: EC2 instances should be distributed across multiple Availability Zones - **Auto Scaling**: Automatically replace failed instances - **Load Balancer**: Distribute traffic across healthy instances in multiple AZs 3. **Why Option A is Correct**: - **Multi-AZ EC2 Auto Scaling**: Ensures EC2 instances are launched across multiple Availability Zones - **Application Load Balancer**: Distributes incoming traffic across healthy instances in multiple AZs - This creates a highly available architecture where if one AZ fails, traffic is routed to instances in other AZs 4. **Why Other Options are Incorrect**: - **Option B**: Taking snapshots and sending them to another region is for disaster recovery, not high availability. It doesn't address the immediate availability issue. - **Option C**: Route 53 latency-based routing alone doesn't solve the single AZ problem. It routes traffic based on latency but doesn't provide instance redundancy across AZs. - **Option D**: While creating a Multi-AZ ALB is good, it doesn't address the EC2 instances being in a single AZ. Route 53 rules alone won't make the application highly available. 5. **Complete Solution**: - Deploy EC2 instances across multiple AZs using Auto Scaling groups - Use Application Load Balancer to distribute traffic - Configure health checks to route traffic only to healthy instances - The RDS Multi-AZ DB instance already provides database high availability This approach ensures the application tier is highly available across multiple Availability Zones, meeting the company's requirements.

Author: LeetQuiz Editorial Team