Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A developer is building a REST API using Amazon API Gateway and AWS Lambda. The API receives a large number of requests with duplicate payloads from the same client within a short time window. To reduce Lambda invocations and improve performance, the developer wants to return the previously computed response for identical requests based on a unique client ID in the header. How can the developer achieve this using API Gateway features?
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
Enable API Gateway caching on the stage and configure the client ID header as a cache key parameter. Set a cache TTL of 5 minutes.
API Gateway caching uses cache key parameters to index responses. By including the client ID header in the cache key, different clients get separate cached responses. The TTL controls how long the response is cached.
B
Distractor review
Configure a usage plan with a quota and throttle settings to limit requests per client ID.
Usage plans limit the number of requests but do not cache responses. They would still invoke the Lambda function for each request, just limiting the rate.
C
Distractor review
Use request validation to reject requests that have the same client ID within 5 minutes.
Request validation checks the structure of the request but cannot detect duplicate payloads or cache responses. It is not designed for this purpose.
D
Distractor review
Reduce the Lambda function's batch size to 1 and implement caching logic inside the function using an external cache like ElastiCache.
While this could work, it requires custom caching logic and adds complexity. The question asks for an API Gateway feature; the correct answer uses a built-in API Gateway capability.
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: Enable API Gateway caching on the stage and configure the client ID header as a cache key parameter. Set a cache TTL of 5 minutes. — API Gateway supports response caching based on cache key parameters. By enabling caching on the stage and configuring the client ID header as a cache key parameter, API Gateway will cache responses per client ID. This avoids invoking the Lambda function for duplicate requests within the cache TTL. Request validation and usage plans do not provide per-client caching. Although reducing batch size might help in other scenarios, it is not relevant to caching.
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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