- A
Return a string from the Lambda handler.
Why wrong: Returning a plain string does not provide the required status code or headers, and API Gateway will not interpret it as a valid HTTP response.
- B
Return a dictionary containing 'statusCode', 'headers', and 'body' with 'body' as a JSON string.
This format satisfies the API Gateway proxy integration contract, allowing the client to receive a proper JSON response.
- C
Use API Gateway integration response and mapping templates to transform the Lambda output.
Why wrong: This approach is not needed with proxy integration; it is more complex and typically used for non-proxy integrations.
- D
Return a JSON object from Lambda and set a Content-Type header in the API Gateway method response.
Why wrong: Even if the Lambda returns a JSON object, the proxy integration requires the structured format; just returning a JSON object without the proper envelope will be misinterpreted.
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. A key principle to apply: lambda proxy integration requires a specific JSON output format from the Lambda function.. 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 serverless REST API using Amazon API Gateway and AWS Lambda. The API should return JSON responses to client requests. The developer is using the Lambda proxy integration. What is the simplest way to return a JSON response from the Lambda function?
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
Return a dictionary containing 'statusCode', 'headers', and 'body' with 'body' as a JSON string.
With Lambda proxy integration, API Gateway passes the entire request to the Lambda function and expects the function to return a specific response format. The simplest way to return a JSON response is to return a dictionary (or object) containing 'statusCode', 'headers', and 'body', where 'body' is a JSON string. This format is required by API Gateway to correctly interpret the Lambda output and forward it to the client.
Key principle: Lambda proxy integration requires a specific JSON output format from the Lambda function.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Return a string from the Lambda handler.
- ✓
Return a dictionary containing 'statusCode', 'headers', and 'body' with 'body' as a JSON string.
- ✗
Use API Gateway integration response and mapping templates to transform the Lambda output.
Why it's wrong here
This approach is not needed with proxy integration; it is more complex and typically used for non-proxy integrations.
- ✗
Return a JSON object from Lambda and set a Content-Type header in the API Gateway method response.
Why it's wrong here
Even if the Lambda returns a JSON object, the proxy integration requires the structured format; just returning a JSON object without the proper envelope will be misinterpreted.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think returning a JSON object directly from Lambda is sufficient, but they overlook the requirement that the body must be a JSON string and the response must include the exact 'statusCode', 'headers', and 'body' keys for API Gateway proxy integration to work correctly.
Detailed technical explanation
How to think about this question
Under the hood, when Lambda proxy integration is enabled, API Gateway passes the entire HTTP request as a JSON event to the Lambda function. The function must return a response in the format { 'statusCode': ..., 'headers': { ... }, 'body': '...' }, where the body must be a string (often a JSON stringified object). If the body is not a string, API Gateway may fail to serialize it, leading to a 502 error. This design allows the Lambda function full control over the HTTP response, including status codes and headers, without needing additional API Gateway configuration.
KKey Concepts to Remember
- Lambda proxy integration requires a specific JSON output format from the Lambda function.
- The Lambda response must include 'statusCode', 'headers', and 'body' as top-level keys.
- The 'body' field in the Lambda response must be a JSON string for JSON responses.
- The 'headers' field should include 'Content-Type': 'application/json' for JSON responses.
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
Lambda proxy integration requires a specific JSON output format from the Lambda function.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
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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 — Lambda proxy integration requires a specific JSON output format from the Lambda function..
What is the correct answer to this question?
The correct answer is: Return a dictionary containing 'statusCode', 'headers', and 'body' with 'body' as a JSON string. — With Lambda proxy integration, API Gateway passes the entire request to the Lambda function and expects the function to return a specific response format. The simplest way to return a JSON response is to return a dictionary (or object) containing 'statusCode', 'headers', and 'body', where 'body' is a JSON string. This format is required by API Gateway to correctly interpret the Lambda output and forward it to the client.
What should I do if I get this DVA-C02 question wrong?
Review lambda proxy integration requires a specific JSON output format from the Lambda function., then practise related DVA-C02 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Lambda proxy integration requires a specific JSON output format from the Lambda function.
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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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