SOA-C02 Question 89
Select 2Your company hosts a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application stores uploaded user files on an Amazon EFS file system shared across all EC2 instances. Recently, you noticed that during maintenance of one of the Availability Zones (AZs), some users experienced application downtime. What steps can you take to ensure the workload remains fault-tolerant during such events?
- A
Ensure the Amazon EFS file system is mounted across multiple Availability Zones.
- B
Configure the Application Load Balancer to route traffic only to healthy targets in all available Availability Zones.
- C
Associate an Elastic IP address with each EC2 instance to ensure connectivity during an AZ failure.
- D
Enable automatic scaling for the EC2 instances to handle increased traffic during AZ failures.
- E
Configure Amazon EFS with a lifecycle policy to automatically move infrequently accessed files to Infrequent Access storage.
Show answer and explanation
Correct answers: A, B
Explanation
To implement a fault-tolerant workload, you need to ensure that critical components like the Amazon EFS file system and the Application Load Balancer are properly configured to operate across multiple Availability Zones. This ensures continued operation even if one AZ becomes unavailable. Elastic IP addresses and lifecycle policies are unrelated to fault tolerance in this scenario, and while automatic scaling is beneficial, it does not directly mitigate downtime caused by AZ failures.
- A. Correct.
Correct: Amazon EFS is a regional service and can be accessed from multiple Availability Zones. Ensuring it is mounted across all AZs allows EC2 instances in other AZs to continue accessing the shared file system during an AZ failure.
- B. Correct.
Correct: The Application Load Balancer health checks ensure traffic is only sent to healthy targets. Configuring it to route traffic across all available AZs improves fault tolerance.
- C. Incorrect.
Incorrect: Elastic IP addresses provide a static public IP for an instance but do not contribute to fault tolerance across Availability Zones.
- D. Incorrect.
Incorrect: While automatic scaling helps manage traffic spikes, it does not directly address fault tolerance during an AZ failure.
- E. Incorrect.
Incorrect: Lifecycle policies in Amazon EFS are used for cost optimization and do not enhance fault tolerance.