The answer is that a bucket policy explicitly denying s3:ListBucket overrides the IAM permissions. This is because AWS evaluates all policies—IAM and resource-based—with an explicit deny taking precedence over any allow, regardless of where the allow is granted. In this scenario, the IAM policy correctly grants s3:ListBucket on the bucket, yet the user can upload and delete objects, confirming that actions allowed by the IAM policy still work. The inability to list objects points directly to a bucket-level deny, which blocks the ListBucket action before the IAM allow can take effect. On the AWS Certified Developer Associate DVA-C02 exam, this tests your understanding of policy evaluation logic and the hierarchy of explicit denies. A common trap is assuming IAM permissions alone guarantee access, but resource-based policies like bucket policies can independently restrict actions. Memory tip: "Deny always wins"—if listing fails despite IAM allows, check the bucket policy for an explicit deny.
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 has attached the IAM policy shown in the exhibit to a user. The user reports that they can upload and delete objects in the bucket 'my-bucket', but cannot list the objects in the bucket. What is the MOST likely reason?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The bucket has a bucket policy that denies s3:ListBucket.
Option A is correct. The ListBucket permission is granted at the bucket level (arn:aws:s3:::my-bucket), but the condition that the user must have s3:ListBucket permission is granted. However, the issue is that the user cannot list objects. The policy looks correct. The most common reason for being unable to list objects despite having ListBucket permission is that the bucket policy denies listing, or the user is trying to list a specific prefix without proper permissions. But in this case, the policy allows ListBucket on the bucket. Option B: The user is using an incorrect API call (e.g., ListObjectsV2) is unlikely. Option C: The bucket is in a different region would not affect permissions. Option D: The user needs s3:GetObject to list? No, listing requires ListBucket. So the correct answer is that the bucket policy overrides the IAM policy. Let me adjust: Actually, the most likely reason is that the bucket has a bucket policy that denies s3:ListBucket. That is option A. Yes.
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 IAM policy is missing the s3:GetObject permission for listing.
Why it's wrong here
Listing objects requires s3:ListBucket, not s3:GetObject.
✓
The bucket has a bucket policy that denies s3:ListBucket.
Why this is correct
An explicit deny in a bucket policy overrides an allow from an IAM policy.
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.
✗
The user is using the ListObjectsV2 API call instead of ListObjects.
Why it's wrong here
Both API calls require the same s3:ListBucket permission.
✗
The bucket is in a different region than the default region configured in the AWS CLI.
Why it's wrong here
Region does not affect IAM permissions.
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 has a bucket policy that denies s3:ListBucket. — Option A is correct. The ListBucket permission is granted at the bucket level (arn:aws:s3:::my-bucket), but the condition that the user must have s3:ListBucket permission is granted. However, the issue is that the user cannot list objects. The policy looks correct. The most common reason for being unable to list objects despite having ListBucket permission is that the bucket policy denies listing, or the user is trying to list a specific prefix without proper permissions. But in this case, the policy allows ListBucket on the bucket. Option B: The user is using an incorrect API call (e.g., ListObjectsV2) is unlikely. Option C: The bucket is in a different region would not affect permissions. Option D: The user needs s3:GetObject to list? No, listing requires ListBucket. So the correct answer is that the bucket policy overrides the IAM policy. Let me adjust: Actually, the most likely reason is that the bucket has a bucket policy that denies s3:ListBucket. That is option A. Yes.
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.
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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