- A
Enable API caching on the stage with a TTL of 300 seconds and configure the client ID as a cache key parameter.
API Gateway caching stores responses for a configurable TTL. By setting the TTL to 300 seconds and including the client ID in the cache key (e.g., as a query string parameter or request header), identical requests will return the cached response without invoking the Lambda function, reducing costs and improving performance.
- B
Enable request validation to reject duplicate requests.
Why wrong: Request validation only validates the request body and parameters against a model. It does not deduplicate requests or cache responses.
- C
Configure a usage plan with a throttle rate to limit requests from each client.
Why wrong: Throttling limits the number of requests but does not provide caching. Duplicate requests would still be processed by Lambda until the throttle limit is reached, and they would not reuse previous responses.
- D
Enable stage variables to store the previous response.
Why wrong: Stage variables are for storing configuration values, not for caching responses. They cannot be used to return cached responses.
DVA-C02 Development with AWS Services Practice Question
This DVA-C02 practice question tests your understanding of development with aws services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer is building a RESTful API using Amazon API Gateway (HTTP API) and AWS Lambda. The API receives a large number of requests with duplicate payloads within a short time window. To improve performance and reduce costs, the developer wants to ensure that if the same request (based on a unique client ID) is sent within 5 minutes, the Lambda function is not invoked again, and the previously calculated response is returned. Which API Gateway feature should the developer use?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Enable API caching on the stage with a TTL of 300 seconds and configure the client ID as a cache key parameter.
Option A is correct because API Gateway's caching feature stores responses from your endpoint for a specified time-to-live (TTL). By setting the TTL to 300 seconds (5 minutes) and configuring the client ID as a cache key parameter, API Gateway will use the client ID to uniquely identify requests. If a request with the same client ID arrives within the TTL window, API Gateway returns the cached response without invoking the Lambda function, reducing costs and improving performance.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable API caching on the stage with a TTL of 300 seconds and configure the client ID as a cache key parameter.
Why this is correct
API Gateway caching stores responses for a configurable TTL. By setting the TTL to 300 seconds and including the client ID in the cache key (e.g., as a query string parameter or request header), identical requests will return the cached response without invoking the Lambda function, reducing costs and improving performance.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Enable request validation to reject duplicate requests.
Why it's wrong here
Request validation only validates the request body and parameters against a model. It does not deduplicate requests or cache responses.
- ✗
Configure a usage plan with a throttle rate to limit requests from each client.
Why it's wrong here
Throttling limits the number of requests but does not provide caching. Duplicate requests would still be processed by Lambda until the throttle limit is reached, and they would not reuse previous responses.
- ✗
Enable stage variables to store the previous response.
Why it's wrong here
Stage variables are for storing configuration values, not for caching responses. They cannot be used to return cached responses.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse throttling (which limits request rate) with caching (which stores and returns previous responses), leading them to pick Option C instead of A.
Detailed technical explanation
How to think about this question
API Gateway caching works by generating a cache key from the configured parameters (e.g., client ID) and the request path. When a cache hit occurs, the response is served directly from the cache without reaching the backend. The TTL value (in seconds) controls how long the cached response is considered fresh; after expiry, the next request triggers a new Lambda invocation. In a real-world scenario, this is ideal for idempotent APIs where repeated identical requests should return the same result, such as payment confirmation lookups or order status checks.
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.
TExam Day Tips
- 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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable API caching on the stage with a TTL of 300 seconds and configure the client ID as a cache key parameter. — Option A is correct because API Gateway's caching feature stores responses from your endpoint for a specified time-to-live (TTL). By setting the TTL to 300 seconds (5 minutes) and configuring the client ID as a cache key parameter, API Gateway will use the client ID to uniquely identify requests. If a request with the same client ID arrives within the TTL window, API Gateway returns the cached response without invoking the Lambda function, reducing costs and improving performance.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
This DVA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DVA-C02 exam.
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