The answer is to check the S3 bucket policy for an explicit deny statement that applies to the IAM role. This is correct because AWS IAM policy evaluation logic dictates that an explicit deny in any policy—whether identity-based (like the IAM role) or resource-based (like the bucket policy)—always overrides any allow. Even if your IAM role grants s3:GetObject, a bucket policy with an explicit deny targeting that role will cause access denied errors, as the deny takes precedence. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of the “explicit deny overrides allow” rule, a common trap where developers assume the IAM role alone is sufficient. A frequent memory tip is to remember the order: default deny, then allow, then explicit deny—the explicit deny is the final word. So when troubleshooting S3 access denied despite IAM role allowing access, always inspect the bucket policy first for any “Deny” effect statements.
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. 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.
An application running on EC2 needs to access an S3 bucket. The developer has assigned an IAM role to the EC2 instance with a policy that allows s3:GetObject on the bucket. However, the application is still getting access denied errors. What should the developer check?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check the S3 bucket policy for an explicit deny statement that applies to the IAM role.
Option B is correct because even if the IAM role attached to the EC2 instance allows s3:GetObject, an S3 bucket policy with an explicit deny statement that applies to that role will override the allow. IAM policy evaluation logic dictates that an explicit deny in any policy (resource-based or identity-based) takes precedence over any allow, resulting in access denied errors.
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.
✗
Check that the application is using HTTPS instead of HTTP.
Why it's wrong here
HTTP is allowed; only an explicit bucket policy requiring HTTPS would cause denial.
✓
Check the S3 bucket policy for an explicit deny statement that applies to the IAM role.
Why this is correct
An explicit deny in the bucket policy overrides any allow from IAM.
Related concept
Read the scenario before looking for a memorised answer.
✗
Check that the EC2 instance has permissions to decrypt the KMS key used by S3.
Why it's wrong here
Only relevant if S3 uses SSE-KMS, but the question does not indicate that.
✗
Check that the EC2 instance is in the same VPC as the S3 bucket.
Why it's wrong here
S3 is a global service; VPC is not required.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume an IAM role with an allow policy is sufficient, overlooking that S3 bucket policies can contain explicit deny statements that override the role's permissions.
Detailed technical explanation
How to think about this question
IAM policy evaluation follows a hierarchy: explicit deny overrides any allow, and if both an identity-based policy (IAM role) and a resource-based policy (bucket policy) apply, the effective permission is the union of all allows minus any explicit denies. A common subtlety is that a bucket policy can deny access to a specific IAM role even if that role has a permissive IAM policy, which is why checking for explicit deny statements in the bucket policy is critical. In real-world scenarios, this often occurs when a bucket policy has a condition like 'Deny if NotIpAddress' that inadvertently blocks the EC2 instance's traffic.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check the S3 bucket policy for an explicit deny statement that applies to the IAM role. — Option B is correct because even if the IAM role attached to the EC2 instance allows s3:GetObject, an S3 bucket policy with an explicit deny statement that applies to that role will override the allow. IAM policy evaluation logic dictates that an explicit deny in any policy (resource-based or identity-based) takes precedence over any allow, resulting in access denied errors.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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