The correct answer is to modify the KMS key policy to include a condition on `kms:SourceVpc` and to create a VPC endpoint for KMS. This works because the key policy condition restricts the cryptographic operation to requests originating from the specified VPC, while the VPC endpoint ensures that all KMS traffic stays within the AWS network and never traverses the public internet. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of the difference between resource-based policies (key policies) and identity-based policies (IAM), as well as the specific condition keys available for KMS. A common trap is to assume an S3 bucket policy or a VPC endpoint for S3 can restrict KMS usage—they cannot, because KMS calls are separate from S3 data plane calls. Remember the mnemonic: "Key policy, not bucket policy, for KMS VPC lockery."
SCS-C02 Data Protection Practice Question
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.
A company is using AWS KMS to encrypt data in Amazon S3. They need to ensure that the KMS key can only be used from within a specific VPC. Which TWO actions should be taken?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a VPC endpoint for AWS KMS.
Option A is correct because a VPC endpoint for KMS is needed to access KMS privately. Option D is correct because a key policy condition using kms:SourceVpc restricts usage to the VPC. Option B is wrong because bucket policy cannot restrict KMS key usage. Option C is wrong because IAM policy alone cannot restrict based on VPC for KMS; it's the key policy. Option E is wrong because a VPC endpoint for S3 does not restrict KMS calls.
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.
✓
Create a VPC endpoint for AWS KMS.
Why this is correct
Enables private connectivity to KMS from the VPC.
Related concept
Read the scenario before looking for a memorised answer.
✗
Attach an IAM policy to the role that denies kms:Decrypt unless the request comes from the VPC.
Why it's wrong here
IAM policies cannot enforce VPC restrictions for KMS; key policy can.
✗
Create a VPC endpoint for Amazon S3.
Why it's wrong here
S3 endpoint does not restrict KMS calls.
✗
Add a bucket policy condition to restrict access to the VPC.
Why it's wrong here
Bucket policy controls S3 access, not KMS key usage.
✓
Modify the KMS key policy to include a condition on kms:SourceVpc.
Why this is correct
This restricts use of the key to requests originating from the specified VPC.
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: Create a VPC endpoint for AWS KMS. — Option A is correct because a VPC endpoint for KMS is needed to access KMS privately. Option D is correct because a key policy condition using kms:SourceVpc restricts usage to the VPC. Option B is wrong because bucket policy cannot restrict KMS key usage. Option C is wrong because IAM policy alone cannot restrict based on VPC for KMS; it's the key policy. Option E is wrong because a VPC endpoint for S3 does not restrict KMS calls.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is using AWS KMS to encrypt sensitive data in Amazon DynamoDB. The security team wants to ensure that the KMS key can only be used from within the company's VPC and not from the internet. The VPC has an interface VPC endpoint for KMS. What should the security team do to enforce this restriction?
easy
A.Make the KMS key Regional and disable cross-Region access
B.Use security group rules to restrict access to the KMS endpoint
C.Create an S3 bucket policy that restricts access to the KMS key
✓ D.Attach a VPC endpoint policy that denies access from outside the VPC
Why D: Option A is correct because attaching a policy to the VPC endpoint that denies access from outside the VPC restricts usage. Option B is wrong because a bucket policy is for S3, not KMS. Option C is wrong because security group rules do not apply to KMS operations; they apply to network traffic. Option D is wrong because making the key regional does not restrict network access.
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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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