- A
Enable CORS in API Gateway and configure the Lambda functions to return the required CORS headers.
Enabling CORS in API Gateway generates an OPTIONS method and configures headers for non-proxy integrations, but for proxy integrations, the Lambda must also return the headers. Both steps are needed to ensure full CORS support.
- B
Configure API Gateway to return CORS headers and Lambda functions can ignore CORS.
Why wrong: If using proxy integration, API Gateway passes the Lambda response directly; if the Lambda does not include CORS headers, the browser will reject the response.
- C
Configure Lambda functions to return CORS headers and API Gateway will pass them through automatically.
Why wrong: API Gateway does pass the headers through, but without an OPTIONS method, preflight requests will fail. The developer should also create an OPTIONS endpoint.
- D
Use a Lambda@Edge function at Amazon CloudFront to add CORS headers.
Why wrong: Lambda@Edge can add headers, but it is an extra service and not the simplest approach for CORS in API Gateway.
DVA-C02 Development with AWS Services Practice Question
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 creating a REST API using Amazon API Gateway and multiple AWS Lambda functions for different endpoints. The API must support CORS for a web application hosted on a different domain. The developer is using Lambda proxy integration. Which configuration is required to enable CORS?
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 CORS in API Gateway and configure the Lambda functions to return the required CORS headers.
With Lambda proxy integration in API Gateway, the entire request and response are passed through to the Lambda function, which must return the HTTP response including status code, headers, and body. To enable CORS, the Lambda function must include the required CORS headers (e.g., Access-Control-Allow-Origin) in its response. While API Gateway can be configured to add CORS headers for non-proxy integrations, with proxy integration the Lambda function is solely responsible for returning all headers.
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 CORS in API Gateway and configure the Lambda functions to return the required CORS headers.
Why this is correct
Enabling CORS in API Gateway generates an OPTIONS method and configures headers for non-proxy integrations, but for proxy integrations, the Lambda must also return the headers. Both steps are needed to ensure full CORS support.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure API Gateway to return CORS headers and Lambda functions can ignore CORS.
Why it's wrong here
If using proxy integration, API Gateway passes the Lambda response directly; if the Lambda does not include CORS headers, the browser will reject the response.
- ✗
Configure Lambda functions to return CORS headers and API Gateway will pass them through automatically.
Why it's wrong here
API Gateway does pass the headers through, but without an OPTIONS method, preflight requests will fail. The developer should also create an OPTIONS endpoint.
- ✗
Use a Lambda@Edge function at Amazon CloudFront to add CORS headers.
Why it's wrong here
Lambda@Edge can add headers, but it is an extra service and not the simplest approach for CORS in API Gateway.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume API Gateway's CORS configuration works universally, but with Lambda proxy integration, the Lambda function has full control over the response headers, making API Gateway's CORS settings ineffective.
Detailed technical explanation
How to think about this question
In Lambda proxy integration, API Gateway sends the raw request to the Lambda function and expects a specific response format: { statusCode, headers, body }. The headers map must include CORS headers like Access-Control-Allow-Origin: '*'. API Gateway's built-in CORS configuration (via OPTIONS method and header mapping) only works with non-proxy (HTTP or AWS service) integrations. A common real-world scenario is when the web app sends preflight OPTIONS requests; the Lambda function must handle those as well by returning the appropriate CORS headers.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 CORS in API Gateway and configure the Lambda functions to return the required CORS headers. — With Lambda proxy integration in API Gateway, the entire request and response are passed through to the Lambda function, which must return the HTTP response including status code, headers, and body. To enable CORS, the Lambda function must include the required CORS headers (e.g., Access-Control-Allow-Origin) in its response. While API Gateway can be configured to add CORS headers for non-proxy integrations, with proxy integration the Lambda function is solely responsible for returning all headers.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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