The answer is a misconfigured SNS topic ARN in the response plan. When an incident manager response plan lambda is not triggering, the most likely cause is that the response plan references the wrong SNS topic Amazon Resource Name (ARN), so notifications never reach the correct topic to invoke the function. Even if the SNS subscription and Lambda resource policy are correctly configured, the response plan itself must point to the exact ARN of the topic that has the Lambda subscription; otherwise, the notification chain breaks before the function is ever called. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how Incident Manager’s response plan acts as the trigger source—it is a common trap to focus on Lambda permissions or SNS subscriptions when the real issue is the plan’s target ARN. A useful memory tip is “Plan points, topic triggers”—the response plan must point to the correct topic ARN for the trigger to fire.
DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 DevOps team uses AWS Systems Manager Incident Manager to manage incidents. They have configured a response plan that sends notifications to an SNS topic, which triggers an AWS Lambda function to post messages to a Slack channel. Recently, the Slack notifications have stopped working. The CloudWatch logs for the Lambda function show no invocations when an incident is created. The SNS topic has a subscription to the Lambda function, and the Lambda function's resource policy allows invocation from SNS. 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 response plan is not configured to send notifications to the correct SNS topic ARN.
Option C is correct because the response plan must have the correct ARN of the SNS topic. Option A is wrong because the logs show no invocations, so the function is not being triggered. Option B is wrong if the function policy allows SNS. Option D is wrong because the function is not invoked.
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 function has a reserved concurrency of 0.
Why it's wrong here
This would cause throttling, but logs would show invocation attempts.
✓
The response plan is not configured to send notifications to the correct SNS topic ARN.
Why this is correct
If the ARN is incorrect, SNS never receives the message.
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 have permission to post to Slack.
Why it's wrong here
The function is not being invoked at all.
✗
The SNS topic's access policy does not allow the Incident Manager to publish to it.
Why it's wrong here
The topic is receiving messages from Incident Manager.
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.
Trap categories for this question
Command / output trap
This would cause throttling, but logs would show invocation attempts.
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 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 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.
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The response plan is not configured to send notifications to the correct SNS topic ARN. — Option C is correct because the response plan must have the correct ARN of the SNS topic. Option A is wrong because the logs show no invocations, so the function is not being triggered. Option B is wrong if the function policy allows SNS. Option D is wrong because the function is not invoked.
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.
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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