DOP-C02 Question 139
Select 3Your organization runs a web application that requires high availability and resilience. The application is deployed in a VPC with private subnets across two Availability Zones. The current architecture includes an Auto Scaling group for the application servers and an Application Load Balancer (ALB) in front of the servers. To meet stricter business continuity requirements, you need to ensure the architecture can handle the failure of an entire Availability Zone without service disruption. Which changes should you implement to meet these requirements?
- A
Configure the Auto Scaling group to span across at least three Availability Zones.
- B
Add a second Application Load Balancer (ALB) in a different Availability Zone and configure DNS failover using Route 53.
- C
Ensure the Application Load Balancer has subnets mapped in at least two Availability Zones.
- D
Increase the minimum instance count in the Auto Scaling group to ensure at least one instance is running in each Availability Zone.
- E
Deploy additional application servers in a third Availability Zone and update the Auto Scaling group to include it.
Show answer and explanation
Correct answers: A, C, D
Explanation
To meet high availability and resilience requirements, the Auto Scaling group should span multiple Availability Zones and have a minimum instance count to maintain instances in each zone. The ALB must also be configured to route traffic across multiple Availability Zones. These steps ensure the architecture can handle a full Availability Zone failure without service disruption, meeting the business continuity requirements.
- A. Correct.
Correct. Configuring the Auto Scaling group to span at least three Availability Zones increases resilience. In case one Availability Zone fails, the Auto Scaling group can launch instances in the remaining zones to maintain application availability.
- B. Incorrect.
Incorrect. Adding a second ALB introduces complexity and is unnecessary for this scenario. ALBs are designed to handle traffic across multiple Availability Zones within a single deployment.
- C. Correct.
Correct. Ensuring the ALB has subnets mapped to at least two Availability Zones is critical for high availability. If one zone becomes unavailable, the load balancer will route traffic to the remaining zones.
- D. Correct.
Correct. Increasing the minimum instance count in the Auto Scaling group ensures that instances are running across all configured Availability Zones, providing fault tolerance.
- E. Incorrect.
Incorrect. While adding a third Availability Zone can improve resilience, the question explicitly requires solutions to handle the loss of an entire Availability Zone. The existing setup with two zones can be made resilient without adding a third zone.