- A
The S3 bucket is in a different region.
Why wrong: Cross-region access is allowed by default.
- B
The S3 bucket uses SSE-KMS encryption and the function lacks kms:Decrypt permissions.
Why wrong: KMS permissions could be an issue, but the error is access denied, not a KMS error.
- C
The Lambda function does not have the correct execution role.
Why wrong: The role has an inline policy allowing PutObject.
- D
The S3 bucket has a bucket policy that denies the request.
A bucket policy can override IAM permissions with an explicit deny.
Question 1,128 of 1,616
Why S3 Bucket Policy Explicit Deny Overrides IAM Permissions
This DVA-C02 practice question tests your understanding of development with aws services. 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 has a Lambda function that writes to an S3 bucket. The IAM role used by the function has an inline policy allowing s3:PutObject on the bucket. However, writes fail with an access denied error. 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 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
✓
The S3 bucket has a bucket policy that denies the request.
Option D is correct because even if the Lambda function's IAM role grants s3:PutObject, an explicit deny in the S3 bucket policy takes precedence over any allow. The access denied error indicates that the request is being evaluated and denied by the bucket policy, which overrides the IAM permission due to AWS's policy evaluation logic (explicit deny > allow).
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 S3 bucket is in a different region.
Why it's wrong here
Cross-region access is allowed by default.
- ✗
The S3 bucket uses SSE-KMS encryption and the function lacks kms:Decrypt permissions.
Why it's wrong here
KMS permissions could be an issue, but the error is access denied, not a KMS error.
- ✗
The Lambda function does not have the correct execution role.
Why it's wrong here
The role has an inline policy allowing PutObject.
- ✓
The S3 bucket has a bucket policy that denies the request.
Why this is correct
A bucket policy can override IAM permissions with an explicit deny.
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
The trap here is that candidates often assume IAM permissions alone are sufficient and overlook that S3 bucket policies can explicitly deny access, which overrides any IAM allow due to AWS's explicit deny precedence.
Detailed technical explanation
How to think about this question
AWS IAM policy evaluation follows a default-deny model where an explicit deny in any policy (resource-based or identity-based) overrides any allow. Bucket policies are resource-based policies that can grant or deny access to principals, including Lambda execution roles. A common real-world scenario is when a bucket policy includes a condition like 'Deny unless a specific VPC endpoint is used,' which would block Lambda functions outside that VPC even if the IAM role allows the action.
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.
TExam Day Tips
- 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.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The S3 bucket has a bucket policy that denies the request. — Option D is correct because even if the Lambda function's IAM role grants s3:PutObject, an explicit deny in the S3 bucket policy takes precedence over any allow. The access denied error indicates that the request is being evaluated and denied by the bucket policy, which overrides the IAM permission due to AWS's policy evaluation logic (explicit deny > allow).
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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Last reviewed: Jul 4, 2026
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.
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