DOP-C02 Question #216: Real Exam Question with Answer & Explanation

Question

A company recently deployed its web application on AWS. The company is preparing for a large- scale sales event and must ensure that the web application can scale to meet the demand. The application's frontend infrastructure includes an Amazon CloudFront distribution that has an Amazon S3 bucket as an origin. The backend infrastructure includes an Amazon API Gateway API, several AWS Lambda functions, and an Amazon Aurora DB cluster. The company's DevOps engineer conducts a load test and identifies that the Lambda functions can fulfil the peak number of requests. However, the DevOps engineer notices request latency during the initial burst of requests. Most of the requests to the Lambda functions produce queries to the database. A large portion of the invocation time is used to establish database connections. Which combination of steps will provide the application with the required scalability? (Choose three.)

Options

• AConfigure a higher reserved concurrency for the Lambda functions.
• BConfigure a higher provisioned concurrency for the Lambda functions.
• CConvert the DB cluster to an Aurora global database. Add additional Aurora Replicas in AWS
• DRefactor the Lambda functions. Move the code blocks that initialize database connections into the
• EUse Amazon RDS Proxy to create a proxy for the Aurora database. Update the Lambda functions

Explanation

To mitigate request latency during initial bursts for Lambda functions burdened by database connection establishment, implement provisioned concurrency, refactor functions to reuse connections, and utilize Amazon RDS Proxy for efficient connection pooling.

Common mistakes.

• A. Configuring higher reserved concurrency only sets a maximum limit for concurrent executions and does not address or mitigate cold start latency or the time spent establishing database connections.
• C. Aurora global databases and additional replicas primarily enhance read scalability and disaster recovery across regions, which does not directly solve the problem of high latency due to database connection establishment within individual Lambda invocations.

Concept tested. AWS Lambda cold start optimization, database connection management, and Amazon RDS Proxy

Reference. https://docs.aws.amazon.com/lambda/latest/dg/invocation-modes.html#invocation-modes-provisioned-concurrency

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