This SCS-C02 practice question tests your understanding of data protection. 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.
Network Topology
Refer to the exhibit. A security engineer is reviewing the CloudWatch Logs configuration for a Lambda function. The log group is encrypted with a customer managed key. The engineer needs to ensure that only the Lambda service can write logs to this log group and that only a specific IAM role can read logs. Which additional configuration is required?
Attach a resource-based policy to the log group that allows only the Lambda service to write logs
Why wrong: Resource-based policies on log groups allow cross-account, not service-specific.
B
Create an S3 bucket policy to allow only Lambda to write to the log group
Why wrong: S3 bucket policy does not apply to CloudWatch Logs.
C
Assign an IAM role to the log group that has permission to write logs
Why wrong: Log groups do not have IAM roles.
D
Add a condition to the KMS key policy that uses kms:ViaService to restrict encryption/decryption to logs.amazonaws.com and a condition that the Lambda function is the source
Allows log service only when Lambda is the source.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a condition to the KMS key policy that uses kms:ViaService to restrict encryption/decryption to logs.amazonaws.com and a condition that the Lambda function is the source
CloudWatch Logs uses a service-linked role to write logs. To restrict writing to the Lambda service, you need to add a condition to the key policy that allows the logs service only when the request comes from Lambda. Option C is correct. Option A is incorrect because a bucket policy is for S3. Option B is incorrect because resource-based policies on log groups are for cross-account access, not to restrict write access. Option D is incorrect because IAM roles cannot be assigned to log groups.
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.
✗
Attach a resource-based policy to the log group that allows only the Lambda service to write logs
Why it's wrong here
Resource-based policies on log groups allow cross-account, not service-specific.
✗
Create an S3 bucket policy to allow only Lambda to write to the log group
Why it's wrong here
S3 bucket policy does not apply to CloudWatch Logs.
✗
Assign an IAM role to the log group that has permission to write logs
Why it's wrong here
Log groups do not have IAM roles.
✓
Add a condition to the KMS key policy that uses kms:ViaService to restrict encryption/decryption to logs.amazonaws.com and a condition that the Lambda function is the source
Why this is correct
Allows log service only when Lambda is the source.
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.
Data Protection — This question tests Data Protection — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a condition to the KMS key policy that uses kms:ViaService to restrict encryption/decryption to logs.amazonaws.com and a condition that the Lambda function is the source — CloudWatch Logs uses a service-linked role to write logs. To restrict writing to the Lambda service, you need to add a condition to the key policy that allows the logs service only when the request comes from Lambda. Option C is correct. Option A is incorrect because a bucket policy is for S3. Option B is incorrect because resource-based policies on log groups are for cross-account access, not to restrict write access. Option D is incorrect because IAM roles cannot be assigned to log groups.
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.
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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