AWS Certified Developer – Associate (DVA-C02) — Question 536

A company has an application that runs on Amazon EC2 instances. The application needs to use dynamic feature flags that will be shared with other applications. The application must poll on an interval for new feature flag values. The values must be cached when they are retrieved.

Which solution will meet these requirements in the MOST operationally efficient way?

Answer options

• A. Store the feature flag values in AWS Secrets Manager. Configure an Amazon ElastiCache node to cache the values by using a lazy loading strategy in the application. Update the application to poll for the values on an interval from ElastiCache.
• B. Store the feature flag values in an Amazon DynamoDB table. Configure DynamoDB Accelerator (DAX) to cache the values by using a lazy loading strategy in the application. Update the application to poll for the values on an interval from DynamoDB.
• C. Store the feature flag values in AWS AppConfig. Configure AWS AppConfig Agent on the EC2 instances to poll for the values on an interval. Update the application to retrieve the values from the AppConfig Agent localhost endpoint.
• D. Store the feature flag values in AWS Systems Manager Parameter Store. Configure the application to poll on an interval. Configure the application to use the AWS SDK to retrieve the values from Parameter Store and to store the values in memory.

Correct answer: C

Explanation

AWS AppConfig is specifically designed for managing and deploying application configurations and feature flags. Utilizing the AWS AppConfig Agent on Amazon EC2 instances offloads the polling and caching responsibilities directly to the agent, which exposes a local endpoint for the application to query. Other solutions involving ElastiCache, DynamoDB Accelerator (DAX), or custom SDK-based in-memory caching require significantly more custom development and infrastructure management, making them less operationally efficient.