The answer is that the AWS Config service does not have permission to invoke the Lambda function. This is the most likely cause because AWS Config requires an explicit resource-based policy on the Lambda function granting it the lambda:InvokeFunction permission, separate from the Lambda function’s own IAM role permissions to modify CloudTrail. Even when the Lambda role has full access to start or update trails, Config itself cannot trigger the function unless it is authorized to do so. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding of cross-service invocation permissions, a common trap where candidates focus only on the Lambda role’s actions and overlook the invoking service’s rights. A reliable memory tip is to think of the “invoker” not the “doer”: Config must be allowed to call Lambda before Lambda can act on CloudTrail.
SCS-C02 Management and Security Governance Practice Question
This SCS-C02 practice question tests your understanding of management and security governance. 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 has a multi-account AWS Organization with 50 accounts. The security team uses AWS CloudTrail to log all API calls and sends the logs to a central S3 bucket in the security account. The team wants to ensure that any attempt to disable CloudTrail logging or delete the trail is detected and automatically remediated within 5 minutes. They have configured an AWS Config rule that triggers an AWS Lambda function when the CloudTrail configuration changes. However, the Lambda function is not being invoked when they test by stopping the trail. The Lambda function's IAM role has permissions to start and update CloudTrail. CloudTrail logs show that the Config rule is evaluating the resource, but the Lambda function is not triggered. 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 AWS Config service does not have permission to invoke the Lambda function.
Option A is correct because AWS Config must have permissions to invoke the Lambda function. Even if the Lambda function has permissions to modify CloudTrail, Config needs permission to invoke it. Option B is wrong because CloudTrail does not need permissions to invoke Lambda. Option C is wrong because the Lambda function has permissions, but Config does not. Option D is wrong because the issue is not with the S3 bucket.
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 S3 bucket policy does not allow CloudTrail to write logs.
Why it's wrong here
This is not related to Lambda invocation.
✗
The Lambda function's IAM role does not have permission to modify CloudTrail.
Why it's wrong here
The role has permissions to start and update, but the issue is invocation.
✗
The CloudTrail trail does not have permission to send logs to the S3 bucket.
Why it's wrong here
This is not related to Lambda invocation.
✓
The AWS Config service does not have permission to invoke the Lambda function.
Why this is correct
Config needs a resource-based policy on the Lambda function allowing it to invoke.
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.
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 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 SCS-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.
Management and Security Governance — This question tests Management and Security Governance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The AWS Config service does not have permission to invoke the Lambda function. — Option A is correct because AWS Config must have permissions to invoke the Lambda function. Even if the Lambda function has permissions to modify CloudTrail, Config needs permission to invoke it. Option B is wrong because CloudTrail does not need permissions to invoke Lambda. Option C is wrong because the Lambda function has permissions, but Config does not. Option D is wrong because the issue is not with the S3 bucket.
What should I do if I get this SCS-C02 question wrong?
Identify which SCS-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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