- A
Enable SSE-KMS on the S3 bucket in Account A and specify the ARN of the KMS key from Account B. S3 will automatically use the key.
Why wrong: Without proper permissions, S3 cannot access the key.
- B
Update the KMS key policy in Account B to grant Account A access to the key. No changes needed in Account A.
Why wrong: The S3 bucket policy must also allow the use of a specific KMS key.
- C
Update the KMS key policy in Account B to grant Account A access to the key, and update the S3 bucket policy in Account A to allow the kms:Encrypt and kms:Decrypt actions for the key.
Both policies are required for cross-account SSE-KMS.
- D
Update the S3 bucket policy in Account A to allow s3:PutObject with the kms:Encrypt permission. No changes needed in Account B.
Why wrong: A KMS key policy in Account B must also grant Account A access to the key.
Quick Answer
The answer is to update the KMS key policy in Account B to grant Account A access to the key, and update the S3 bucket policy in Account A to allow the kms:Encrypt and kms:Decrypt actions for the key. This is correct because cross-account SSE-KMS requires a two-way permission bridge: the KMS key policy in the key-owning account must explicitly authorize the external account to use the key, while the S3 bucket policy in the bucket-owning account must delegate those same KMS actions to the bucket’s principal, ensuring the service can call KMS on the uploader’s behalf. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding that S3 does not automatically inherit KMS permissions across accounts—both policies must be explicitly configured, and a common trap is assuming a bucket policy alone suffices. Remember the “double grant” rule: the key policy says “you may use me,” and the bucket policy says “use this key for my objects.”
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 designing a new data lake on Amazon S3. The data is ingested from various sources and must be encrypted at rest. The company has a strict requirement to use an AWS KMS customer master key (CMK) that is stored in a different AWS account for additional security. The S3 bucket is in Account A, and the KMS key is in Account B. Which steps are necessary to enable server-side encryption with AWS KMS (SSE-KMS) for objects in the S3 bucket?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Update the KMS key policy in Account B to grant Account A access to the key, and update the S3 bucket policy in Account A to allow the kms:Encrypt and kms:Decrypt actions for the key.
Option D is correct because cross-account KMS access requires both a key policy in Account B granting Account A permission to use the key, and an S3 bucket policy in Account A that allows the necessary actions and specifies the KMS key. Option A is wrong because the KMS key policy must allow Account A to use the key, but the S3 bucket policy also needs to be updated. Option B is wrong because the KMS key policy must explicitly grant access to Account A. Option C is wrong because S3 does not automatically use the KMS key; the bucket policy must specify the key.
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.
- ✗
Enable SSE-KMS on the S3 bucket in Account A and specify the ARN of the KMS key from Account B. S3 will automatically use the key.
Why it's wrong here
Without proper permissions, S3 cannot access the key.
- ✗
Update the KMS key policy in Account B to grant Account A access to the key. No changes needed in Account A.
Why it's wrong here
The S3 bucket policy must also allow the use of a specific KMS key.
- ✓
Update the KMS key policy in Account B to grant Account A access to the key, and update the S3 bucket policy in Account A to allow the kms:Encrypt and kms:Decrypt actions for the key.
Why this is correct
Both policies are required for cross-account SSE-KMS.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Update the S3 bucket policy in Account A to allow s3:PutObject with the kms:Encrypt permission. No changes needed in Account B.
Why it's wrong here
A KMS key policy in Account B must also grant Account A access to the key.
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 SAP-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.
- →
Design for New Solutions — study guide chapter
Learn the concepts, then practise the questions
- →
Design for New Solutions practice questions
Targeted practice on this topic area only
- →
All SAP-C02 questions
1,746 questions across all exam domains
- →
AWS Certified Solutions Architect Professional SAP-C02 study guide
Full concept coverage aligned to exam objectives
- →
SAP-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related SAP-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Design Solutions for Organizational Complexity practice questions
Practise SAP-C02 questions linked to Design Solutions for Organizational Complexity.
Design for New Solutions practice questions
Practise SAP-C02 questions linked to Design for New Solutions.
Continuous Improvement for Existing Solutions practice questions
Practise SAP-C02 questions linked to Continuous Improvement for Existing Solutions.
Accelerate Workload Migration and Modernization practice questions
Practise SAP-C02 questions linked to Accelerate Workload Migration and Modernization.
SAA-C03 VPC practice questions
Practise SAP-C02 questions linked to SAA-C03 VPC.
SAA-C03 S3 lifecycle policy questions
Practise SAP-C02 questions linked to SAA-C03 S3 lifecycle policy questions.
SAA-C03 RDS Multi-AZ questions
Practise SAP-C02 questions linked to SAA-C03 RDS Multi-AZ questions.
SAA-C03 IAM policy practice questions
Practise SAP-C02 questions linked to SAA-C03 IAM policy.
SAA-C03 Route 53 failover questions
Practise SAP-C02 questions linked to SAA-C03 Route 53 failover questions.
SAA-C03 CloudFront practice questions
Practise SAP-C02 questions linked to SAA-C03 CloudFront.
SAA-C03 NAT gateway questions
Practise SAP-C02 questions linked to SAA-C03 NAT gateway questions.
SAA-C03 VPC endpoint questions
Practise SAP-C02 questions linked to SAA-C03 VPC endpoint questions.
Practice this exam
Start a free SAP-C02 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this SAP-C02 question test?
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Update the KMS key policy in Account B to grant Account A access to the key, and update the S3 bucket policy in Account A to allow the kms:Encrypt and kms:Decrypt actions for the key. — Option D is correct because cross-account KMS access requires both a key policy in Account B granting Account A permission to use the key, and an S3 bucket policy in Account A that allows the necessary actions and specifies the KMS key. Option A is wrong because the KMS key policy must allow Account A to use the key, but the S3 bucket policy also needs to be updated. Option B is wrong because the KMS key policy must explicitly grant access to Account A. Option C is wrong because S3 does not automatically use the KMS key; the bucket policy must specify the key.
What should I do if I get this SAP-C02 question wrong?
Identify which SAP-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 →
Last reviewed: Jun 20, 2026
This SAP-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 SAP-C02 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.