The correct answer is to set the Lambda event source mapping to not delete messages from the queue on failure. This configuration ensures that when a Lambda function fails to process an SQS message, the message remains in the queue and becomes visible again after the visibility timeout expires, allowing the Lambda service to retry processing it. This directly addresses the need for a Lambda SQS message not lost on failure scenario, as the event source mapping controls message deletion—only removing messages upon successful processing. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of how Lambda integrates with SQS as an event source, often appearing as a trap where candidates confuse dead-letter queues (DLQs) with retry logic. A common mistake is thinking a DLQ handles initial failures, but DLQs only capture messages after all retries are exhausted. Remember the memory tip: "Delete only on success, or the message stays for the next attempt."
DOP-C02 Resilient Cloud Solutions Practice Question
This DOP-C02 practice question tests your understanding of resilient cloud solutions. 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 company uses AWS Lambda to process messages from an SQS queue. They need to ensure that if the Lambda function fails, the message is not lost and can be processed again. Which configuration is required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set the Lambda event source mapping to not delete messages from the queue on failure.
Option C is correct because the Lambda event source mapping can be configured to delete messages only after successful processing; if the function fails, the message remains in the queue. Option A is incorrect because a DLQ is for messages that repeatedly fail, not for retry. Option B is incorrect because the visibility timeout should be set longer than the function timeout to avoid other consumers picking up the message. Option D is incorrect because SQS itself does not retry; the Lambda service handles retries based on the event source mapping.
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.
✗
Set the visibility timeout to less than the Lambda function timeout.
Why it's wrong here
This could cause the message to become visible again before processing completes, leading to duplicates.
✗
Enable SQS redrive policy to retry messages.
Why it's wrong here
SQS redrive policy moves messages to a DLQ, not retry.
✗
Configure a dead-letter queue (DLQ) on the SQS queue.
Why it's wrong here
A DLQ captures messages after several failures but does not ensure retries.
✓
Set the Lambda event source mapping to not delete messages from the queue on failure.
Why this is correct
This ensures the message remains in the queue for retry.
Related concept
Read the scenario before looking for a memorised answer.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which DOP-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.
Resilient Cloud Solutions — This question tests Resilient Cloud Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set the Lambda event source mapping to not delete messages from the queue on failure. — Option C is correct because the Lambda event source mapping can be configured to delete messages only after successful processing; if the function fails, the message remains in the queue. Option A is incorrect because a DLQ is for messages that repeatedly fail, not for retry. Option B is incorrect because the visibility timeout should be set longer than the function timeout to avoid other consumers picking up the message. Option D is incorrect because SQS itself does not retry; the Lambda service handles retries based on the event source mapping.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This DOP-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 DOP-C02 exam.
Question Discussion
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