- A
Return a JSON object with 'status_code' and 'message' keys.
Why wrong: The required key is 'statusCode' (camelCase), not 'status_code'. Also, 'body' is required instead of 'message'.
- B
Throw an exception with a message that includes the HTTP status code.
Why wrong: Throwing an exception causes API Gateway to return a 502 Bad Gateway error, not the custom status code.
- C
Return a JSON object with 'errorMessage' and 'errorType' keys.
Why wrong: This format is used for Lambda function errors in non-proxy integrations, but with proxy integration, the response must be in the specific format.
- D
Return a JSON object with keys 'statusCode', 'headers', and 'body' where 'statusCode' is 404 and 'body' contains the error message.
For Lambda proxy integration, the Lambda function must return a response in the format { 'statusCode': ..., 'headers': ..., 'body': ... } to control the HTTP response.
Lambda Proxy Integration: Custom HTTP Status Codes
This DVA-C02 practice question tests your understanding of development with aws services. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 serverless application using AWS Lambda and Amazon API Gateway REST API. The API Gateway is configured to use a Lambda proxy integration. The developer wants to return a custom error message with a specific HTTP status code (e.g., 404) when a resource is not found. How should the developer implement this?
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 JSON object with keys 'statusCode', 'headers', and 'body' where 'statusCode' is 404 and 'body' contains the error message.
Option D is correct because with Lambda proxy integration in API Gateway, the Lambda function must return a response in the exact format that API Gateway expects: a JSON object with 'statusCode' (integer), 'headers' (object), and 'body' (string). This allows the developer to set a custom HTTP status code like 404 and include a custom error message in the body. API Gateway will then map this response directly to the HTTP response sent to the client.
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.
- ✗
Return a JSON object with 'status_code' and 'message' keys.
Why it's wrong here
The required key is 'statusCode' (camelCase), not 'status_code'. Also, 'body' is required instead of 'message'.
- ✗
Throw an exception with a message that includes the HTTP status code.
Why it's wrong here
Throwing an exception causes API Gateway to return a 502 Bad Gateway error, not the custom status code.
- ✗
Return a JSON object with 'errorMessage' and 'errorType' keys.
Why it's wrong here
This format is used for Lambda function errors in non-proxy integrations, but with proxy integration, the response must be in the specific format.
- ✓
Return a JSON object with keys 'statusCode', 'headers', and 'body' where 'statusCode' is 404 and 'body' contains the error message.
Why this is correct
For Lambda proxy integration, the Lambda function must return a response in the format { 'statusCode': ..., 'headers': ..., 'body': ... } to control the HTTP response.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the Lambda proxy integration response format with the standard Lambda error response format (errorMessage/errorType) or assume that simply throwing an exception will propagate the status code, but AWS requires a specific structured success response to control the HTTP status code.
Detailed technical explanation
How to think about this question
Under the hood, when using Lambda proxy integration, API Gateway passes the entire client request to Lambda and expects the function to return a response with a specific structure: the 'statusCode' must be an integer, 'headers' must be a key-value map (e.g., for CORS or content-type), and 'body' must be a JSON string (not a JSON object). A common pitfall is forgetting to stringify the body, which causes API Gateway to fail with a 502 error. In real-world scenarios, this pattern is essential for building RESTful APIs where you need fine-grained control over status codes, such as returning 201 for resource creation or 409 for conflicts.
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 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.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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: Return a JSON object with keys 'statusCode', 'headers', and 'body' where 'statusCode' is 404 and 'body' contains the error message. — Option D is correct because with Lambda proxy integration in API Gateway, the Lambda function must return a response in the exact format that API Gateway expects: a JSON object with 'statusCode' (integer), 'headers' (object), and 'body' (string). This allows the developer to set a custom HTTP status code like 404 and include a custom error message in the body. API Gateway will then map this response directly to the HTTP response sent to the client.
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.
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Last reviewed: Jul 4, 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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