The answer is a missing kms:Decrypt permission. When an S3 bucket uses SSE-KMS encryption, the Lambda function must have explicit kms:Decrypt permission in its execution role to decrypt the object before writing or reading it, even if s3:PutObject and s3:GetObject are allowed. The provided policy grants S3 actions but omits the required KMS action, causing the AccessDenied error. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how S3 encryption interacts with IAM permissions—a common trap is assuming S3 permissions alone suffice for encrypted buckets. Remember that SSE-KMS decryption happens at the KMS level, not S3, so the role needs both s3:PutObject and kms:Decrypt (and often kms:GenerateDataKey for writes). Memory tip: "S3 for the bucket, KMS for the key—don't forget the decrypt."
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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 developer is troubleshooting an AWS Lambda function that writes to an S3 bucket. The function is failing with an 'AccessDenied' error. The Lambda execution role has the following policy. What is the likely issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The bucket uses SSE-KMS encryption, and the role lacks kms:Decrypt permission.
Option A is correct because the policy only grants access to objects in the bucket, not to the bucket itself for operations like ListBucket, but for PutObject, the resource is correct. However, the error may be due to a missing permission for s3:PutObject on the bucket level if the bucket policy also requires it. Actually, the most common issue for PutObject is the resource ARN, which is correct. But if the bucket is encrypted, you need kms:Decrypt permissions. Option A points to missing KMS permissions, which is plausible. Option B is wrong because the resource is correct. Option C is wrong because S3 does not require s3:ListBucket for PutObject. Option D is wrong because the action is allowed.
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 resource ARN should be 'arn:aws:s3:::my-bucket' instead of 'my-bucket/*'.
Why it's wrong here
For PutObject, the resource must be the object ARN.
✗
The action should be 's3:PutObject' only, not 's3:GetObject'.
Why it's wrong here
Having extra permissions does not cause AccessDenied.
✗
The role is missing s3:ListBucket permission.
Why it's wrong here
ListBucket is not required for PutObject.
✓
The bucket uses SSE-KMS encryption, and the role lacks kms:Decrypt permission.
Why this is correct
Without KMS permissions, PutObject fails with AccessDenied.
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 DVA-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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The bucket uses SSE-KMS encryption, and the role lacks kms:Decrypt permission. — Option A is correct because the policy only grants access to objects in the bucket, not to the bucket itself for operations like ListBucket, but for PutObject, the resource is correct. However, the error may be due to a missing permission for s3:PutObject on the bucket level if the bucket policy also requires it. Actually, the most common issue for PutObject is the resource ARN, which is correct. But if the bucket is encrypted, you need kms:Decrypt permissions. Option A points to missing KMS permissions, which is plausible. Option B is wrong because the resource is correct. Option C is wrong because S3 does not require s3:ListBucket for PutObject. Option D is wrong because the action is allowed.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-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 →
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.
This DVA-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 DVA-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.