Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
An AWS Lambda function processes messages from an Amazon SQS queue and writes results to an Amazon DynamoDB table. The function is configured with a reserved concurrency of 5 and a batch size of 10. CloudWatch metrics show high throttling and a growing queue backlog. The function's execution time averages 1 second per message. What is the MOST effective action to reduce throttling while improving throughput?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Increase the reserved concurrency to 20.
Increasing reserved concurrency allows Lambda to scale and invoke more function instances concurrently. This directly reduces throttling and allows the function to process more messages from the SQS queue simultaneously, improving throughput and reducing backlog.
B
Distractor review
Increase the batch size to 100.
Increasing batch size may cause each invocation to take longer, potentially leading to timeouts if the function cannot process 100 messages within its timeout. It does not address the underlying concurrency limitation and may even increase throttling because fewer invocations happen but each takes longer.
C
Distractor review
Decrease the reserved concurrency to 2.
Decreasing reserved concurrency would make throttling worse by further limiting the number of concurrent executions. This would increase the backlog.
D
Distractor review
Increase the provisioned write capacity of the DynamoDB table.
The issue is Lambda throttling, not DynamoDB throttling. Increasing DynamoDB capacity does not help Lambda process more messages. It may become relevant later if DynamoDB becomes a bottleneck, but the immediate problem is Lambda throttling.
Common exam trap
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Technical deep dive
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related DVA-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer is building a REST API using Amazon API Gateway that will serve static content from an Amazon S3 bucket. The API should cache responses for frequently accessed objects to reduce latency. Which API Gateway feature should the developer enable?
Question 2
A developer is running a web application on multiple Amazon EC2 instances behind an Application Load Balancer (ALB). The application needs to store user session state that must be available across all instances. The session data is small and temporary but must survive individual instance failures. Which AWS service should the developer use to store this session state?
Question 3
A developer has an AWS Lambda function that processes messages from an Amazon SQS standard queue. The function is idempotent and currently has a batch size of 10. The developer wants to increase throughput and increases the batch size to 100. After the change, CloudWatch metrics show a significant increase in throttles and the queue backlog is growing. The function's reserved concurrency is set to 10. What is the most effective action to resolve the throttling and improve throughput?
Question 4
A developer is managing an application running on Amazon EC2 instances behind an Application Load Balancer. Users report that the application becomes unresponsive after several hours, and restarting the instance temporarily fixes the issue. The developer suspects a memory leak but cannot add custom instrumentation. Which AWS service can collect memory utilization metrics and help identify the memory leak with minimal configuration?
Question 5
A developer is building a serverless web application using AWS Lambda and Amazon DynamoDB. The application needs to perform complex aggregations on data stored in DynamoDB. Which AWS service should the developer use to perform these aggregations efficiently without reading all the data into Lambda?
Question 6
A developer has an Amazon S3 bucket containing private user documents. The application must generate a time-limited URL for users to download their own documents without requiring the users to have AWS credentials. Which solution should the developer use?
FAQ
Questions learners often ask
What does this DVA-C02 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: Increase the reserved concurrency to 20. — The throttling occurs because the function's reserved concurrency of 5 is too low to handle the incoming message volume. Increasing reserved concurrency allows Lambda to scale and process more messages concurrently, reducing backlog and throttling. Increasing batch size would cause each invocation to process more messages, but that does not directly address concurrency limits and may cause timeouts if the function cannot finish within the lambda timeout. Decreasing reserved concurrency would worsen throttling. Increasing DynamoDB write capacity may help avoid throttling from DynamoDB but the primary issue is Lambda throttling.
What should I do if I get this DVA-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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