The correct answer is to verify the API Gateway integration response and mapping templates. This is the right first step because when an API Gateway endpoint returns a 500 error but the Lambda function logs show no errors, the failure is occurring after Lambda successfully executes—meaning API Gateway cannot properly transform the Lambda’s response into the HTTP response expected by the client. The integration response and mapping templates define how API Gateway maps the Lambda output (including status codes and body) to the HTTP response; if these are misconfigured or missing, API Gateway throws an internal server error even though the Lambda itself ran perfectly. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of the API Gateway request/response pipeline, specifically the difference between Lambda execution errors and API Gateway integration errors. A common trap is to immediately check Lambda logs or IAM permissions, but the absence of Lambda errors points squarely to the integration layer. Memory tip: “Lambda logs clean, check the in-between—mapping templates are the translation scene.”
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 has deployed a serverless application using AWS SAM. After a recent update, the API Gateway endpoints return 500 errors. The Lambda function logs show no errors. What should the developer investigate first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify the API Gateway integration response and mapping templates.
Option D is correct because when API Gateway returns 500 errors but Lambda logs show no errors, the issue is typically in the API Gateway integration response or mapping templates. API Gateway may fail to transform the Lambda response into the expected format, causing an internal server error without the Lambda function ever throwing an exception.
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.
✗
Increase the Lambda function timeout.
Why it's wrong here
Timeout would cause Lambda to return an error, which would appear in logs.
✗
Check the Lambda function's reserved concurrency.
Why it's wrong here
Reserved concurrency would cause throttling (429), not 500.
✗
Review the CloudFormation stack events for any failures.
Why it's wrong here
Stack events show deployment success/failure, not runtime errors.
✓
Verify the API Gateway integration response and mapping templates.
Why this is correct
Incorrect mapping can cause API Gateway to return 500 even if Lambda executes successfully.
Clue confirmation
The clue word "first" in the question point toward this answer.
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 assume 500 errors always originate from the Lambda function, but the question explicitly states Lambda logs show no errors, forcing the candidate to look at the API Gateway integration layer instead.
Trap categories for this question
Command / output trap
Stack events show deployment success/failure, not runtime errors.
Detailed technical explanation
How to think about this question
API Gateway integration responses define how to map the Lambda function's response (including status codes, headers, and body) to the HTTP response sent to the client. If the mapping template or integration response status code regex is misconfigured, API Gateway may fail to parse the Lambda output, resulting in a 500 error even though the Lambda executed successfully. This is a common pitfall when updating response schemas or switching between proxy and non-proxy integrations.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Verify the API Gateway integration response and mapping templates. — Option D is correct because when API Gateway returns 500 errors but Lambda logs show no errors, the issue is typically in the API Gateway integration response or mapping templates. API Gateway may fail to transform the Lambda response into the expected format, causing an internal server error without the Lambda function ever throwing an exception.
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.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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