The answer is that the KMS key policy does not grant CloudTrail permission to use the key. When you enable SSE-KMS on an S3 bucket that CloudTrail is writing to, CloudTrail must have explicit decrypt and generate-data-key permissions on the customer-managed KMS key; without these, the service cannot encrypt the log files before delivery, causing the trail to fail silently. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of how KMS key policies interact with AWS services—a common trap is assuming that enabling SSE-KMS on the bucket automatically works, or that the bucket policy alone controls access. Remember that CloudTrail acts as a separate principal that must be listed in the key policy, not just the bucket policy. A useful memory tip: “Key policy first, bucket policy second—CloudTrail needs the key to encrypt before it can put.”
SCS-C02 Security Logging and Monitoring Practice Question
This SCS-C02 practice question tests your understanding of security logging and monitoring. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 CloudTrail and wants to ensure that logs are encrypted at rest using a customer-managed KMS key. The CloudTrail trail is configured to deliver logs to an S3 bucket. After enabling SSE-KMS on the S3 bucket, the logs are not being delivered. 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 KMS key policy does not grant CloudTrail permission to use the key.
Option A is correct because CloudTrail needs explicit permissions to use the KMS key for encrypting log files. Option B is incorrect because CloudTrail can use KMS keys from other accounts. Option C is incorrect because CloudTrail supports SSE-KMS. Option D is incorrect because bucket policies for CloudTrail must allow `s3:PutObject`.
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.
✗
CloudTrail does not support SSE-KMS.
Why it's wrong here
CloudTrail does support SSE-KMS.
✗
The KMS key is in a different AWS account.
Why it's wrong here
CloudTrail supports cross-account KMS keys.
✗
The S3 bucket policy does not allow CloudTrail to write logs.
Why it's wrong here
This would prevent delivery regardless of encryption.
✓
The KMS key policy does not grant CloudTrail permission to use the key.
Why this is correct
CloudTrail must have kms:GenerateDataKey and kms:Decrypt permissions.
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.
Security Logging and Monitoring — This question tests Security Logging and Monitoring — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The KMS key policy does not grant CloudTrail permission to use the key. — Option A is correct because CloudTrail needs explicit permissions to use the KMS key for encrypting log files. Option B is incorrect because CloudTrail can use KMS keys from other accounts. Option C is incorrect because CloudTrail supports SSE-KMS. Option D is incorrect because bucket policies for CloudTrail must allow `s3:PutObject`.
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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This SCS-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 SCS-C02 exam.
Question Discussion
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