The answer is the Lambda function returning an unhandled exception, as this is the most likely cause of an API Gateway 502 Bad Gateway error with Lambda integration. When a Lambda function throws an error—such as a runtime exception, a timeout, or an unhandled code failure—API Gateway cannot parse the response into a valid HTTP format, resulting in a 502 status. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how API Gateway interprets Lambda responses versus common misconfigurations like throttling (which yields 429) or IAM permission issues (which yield 403). A frequent trap is assuming network or permission problems cause 502s, but the exam emphasizes that Lambda must return a properly formatted JSON object, even for errors. Remember the memory tip: “502 means Lambda blew up, not the gateway”—if you see a 502, always check your Lambda function’s error handling and logs first.
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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 company is using Amazon API Gateway to expose a REST API. The API is integrated with an AWS Lambda function. Lately, the API is returning 502 Bad Gateway errors. What is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Lambda function is returning an unhandled exception.
Option B is correct because 502 errors in API Gateway with Lambda integration typically indicate that the Lambda function returned an error. Option A is wrong because throttling would cause 429 Too Many Requests. Option C is wrong because IAM permissions would cause 403 Forbidden. Option D is wrong because API keys are used for client authentication, not for backend integration.
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.
✗
The API Gateway request throttling limit has been exceeded.
Why it's wrong here
Throttling returns 429 errors, not 502.
✗
The API Gateway API key is invalid.
Why it's wrong here
Invalid API keys cause 403 errors.
✓
The Lambda function is returning an unhandled exception.
Why this is correct
API Gateway expects a specific response format; any error from Lambda results in a 502.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Lambda function's execution role does not allow API Gateway to invoke it.
Why it's wrong here
Permissions issues cause 403 errors, not 502.
Common exam traps
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.
Detailed technical explanation
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.
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.
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Lambda function is returning an unhandled exception. — Option B is correct because 502 errors in API Gateway with Lambda integration typically indicate that the Lambda function returned an error. Option A is wrong because throttling would cause 429 Too Many Requests. Option C is wrong because IAM permissions would cause 403 Forbidden. Option D is wrong because API keys are used for client authentication, not for backend integration.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Amazon API Gateway with a Lambda integration. The API returns a 502 Bad Gateway error for some requests. The Lambda function writes logs to CloudWatch. Which steps should a developer take to troubleshoot this issue? (Select the BEST combination.)
hard
A.Enable API Gateway detailed metrics and create a dashboard.
B.Verify the IAM role permissions for API Gateway to invoke Lambda.
C.Check the API Gateway throttling settings and request limit.
✓ D.Increase the Lambda function timeout and review the CloudWatch logs for errors.
Why D: Option C is correct because increasing Lambda timeout and checking CloudWatch logs can identify if the function is timing out or has an error. Option A is wrong because API Gateway throttling returns 429, not 502. Option B is wrong because IAM permissions would cause 403. Option D is wrong because enabling detailed metrics helps but doesn't directly troubleshoot 502.
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.