SAA-C03 Question 164
Select 3A startup is hosting a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application is critical to the business and must be highly available and fault-tolerant. Currently, the EC2 instances are deployed in a single Availability Zone (AZ). What changes should the Solutions Architect make to improve the architecture's availability and fault tolerance?
- A
Deploy the EC2 instances across multiple Availability Zones.
- B
Add an Auto Scaling group to manage the EC2 instances.
- C
Migrate the application to a single Amazon RDS instance for better performance.
- D
Enable cross-zone load balancing on the Application Load Balancer.
- E
Provision the EC2 instances in multiple AWS Regions.
Show answer and explanation
Correct answers: A, B, D
Explanation
To design a highly available and fault-tolerant architecture, EC2 instances should be deployed across multiple Availability Zones to mitigate the impact of an AZ failure. An Auto Scaling group ensures that EC2 instances are dynamically managed based on demand, while enabling cross-zone load balancing on the ALB ensures even traffic distribution across all AZs. These changes together enhance the architecture's resilience and availability.
- A. Correct.
Deploying EC2 instances across multiple Availability Zones ensures that the application continues to run even if one AZ becomes unavailable. This improves both availability and fault tolerance.
- B. Correct.
Adding an Auto Scaling group allows the system to automatically adjust the number of EC2 instances in response to load, ensuring both high availability and optimal resource utilization.
- C. Incorrect.
Migrating to a single Amazon RDS instance does not improve fault tolerance because a single instance in one AZ is still a single point of failure.
- D. Correct.
Enabling cross-zone load balancing on the ALB ensures that traffic is distributed evenly across EC2 instances in all AZs, further improving availability.
- E. Incorrect.
Deploying EC2 instances in multiple Regions is unnecessary unless the application specifically requires global fault tolerance. This is typically more complex and costly than using multiple AZs.