DVA-C02 Development with AWS Services Practice Question
This DVA-C02 practice question tests your understanding of development with aws services. 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.
An API Gateway REST API invokes Lambda synchronously. Clients receive 502 responses after a deployment, but Lambda logs show a successful business operation. What is the most likely issue?
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 proxy integration response format is invalid
Lambda proxy integration requires the response to be in a specific JSON format: `{"statusCode": ..., "headers": ..., "body": ...}`. If the Lambda function returns a plain string or an object missing these keys, API Gateway cannot map it to an HTTP response, resulting in a 502 Internal Server Error. The successful business operation in logs confirms the Lambda code ran correctly, but the malformed response format causes the gateway error.
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 Lambda execution role lacks dynamodb:PutItem
Why it's wrong here
This does not meet the stated requirement as directly as the correct option.
✓
The Lambda proxy integration response format is invalid
Why this is correct
Correct for the stated requirement.
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 API cache TTL is too short
Why it's wrong here
This does not meet the stated requirement as directly as the correct option.
✗
The API stage has X-Ray tracing enabled
Why it's wrong here
This does not meet the stated requirement as directly as the correct option.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates see 'successful business operation' in logs and assume the Lambda is fine, overlooking that API Gateway proxy integration enforces a strict response contract, not just any valid return value.
Detailed technical explanation
How to think about this question
Under the hood, API Gateway proxy integration passes the entire Lambda response as the HTTP response. The Lambda must return a JSON object with `statusCode` (integer), `headers` (object), and `body` (string). If the body is not a string (e.g., a JSON object), API Gateway serializes it incorrectly, leading to a 502. In real-world scenarios, developers often forget to stringify the body or omit required keys, especially when migrating from non-proxy integration.
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.
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.
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: The Lambda proxy integration response format is invalid — Lambda proxy integration requires the response to be in a specific JSON format: `{"statusCode": ..., "headers": ..., "body": ...}`. If the Lambda function returns a plain string or an object missing these keys, API Gateway cannot map it to an HTTP response, resulting in a 502 Internal Server Error. The successful business operation in logs confirms the Lambda code ran correctly, but the malformed response format causes the gateway error.
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: "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.
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Question Discussion
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