SOA-C02 Question 49
Select 3Your company hosts a critical web application on AWS using an Auto Scaling group across multiple Availability Zones (AZs) behind an Application Load Balancer (ALB). Recently, you noticed that when one of the AZs becomes unavailable, there is a significant delay in scaling the instances in the remaining AZs, leading to performance degradation. What steps should you take to improve the application's reliability and ensure faster recovery during AZ outages?
- A
Enable Auto Scaling group metrics collection and configure an appropriate cooldown period.
- B
Increase the minimum and desired instance count in the Auto Scaling group.
- C
Enable Elastic Load Balancer cross-zone load balancing.
- D
Configure Auto Scaling to prioritize launching instances in available AZs when one AZ fails.
- E
Manually add instances to the remaining AZs during an outage to handle the load.
Show answer and explanation
Correct answers: A, C, D
Explanation
To improve reliability and ensure faster recovery during AZ outages, you must optimize your Auto Scaling group and Elastic Load Balancer settings. Enabling metrics and tuning the cooldown period ensures scaling activities are efficient. Cross-zone load balancing ensures traffic is evenly distributed, preventing overloading of certain AZs. Configuring Auto Scaling to prioritize unaffected AZs ensures capacity is restored quickly. These actions together improve application reliability and minimize downtime.
- A. Correct.
Enabling Auto Scaling group metrics collection allows you to monitor scaling activities and optimize the cooldown period to ensure faster recovery during load changes. This action helps improve reliability.
- B. Incorrect.
Increasing the minimum and desired instance count can improve overall capacity, but it does not address the specific problem of slow recovery during an AZ outage.
- C. Correct.
Enabling Elastic Load Balancer cross-zone load balancing ensures that traffic is distributed evenly across instances in all AZs, which helps maintain performance when one AZ fails.
- D. Correct.
Configuring Auto Scaling to prioritize launching instances in available AZs ensures that capacity is restored quickly in unaffected AZs during an outage, improving reliability.
- E. Incorrect.
Manually adding instances is not a scalable or reliable solution. AWS services like Auto Scaling and Elastic Load Balancing are designed to handle such scenarios automatically.