The answer is a bucket policy condition that does not match the request context. Even when an EC2 instance has a correct IAM role and instance profile granting S3 access, the bucket policy acts as a separate authorization layer that can override those permissions. If the policy includes a condition like aws:SourceIp, aws:SourceVpce, or aws:SecureTransport, and the request from the EC2 instance fails to satisfy that condition, the policy evaluates to an explicit deny, blocking the read operation. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of how IAM policies and resource-based policies interact, with the common trap being that developers assume the IAM role alone is sufficient. Remember that bucket policies can impose additional constraints beyond identity—they are not just about who you are, but also about how and from where you are making the request. Memory tip: “Role gets you in, but the bucket policy sets the rules of the house.”
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 uses an IAM role to allow an EC2 instance to access an S3 bucket. The bucket policy also grants access to the role. An application running on the instance is unable to read objects. The instance has the correct instance profile. 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The bucket policy has a condition that does not match the request context.
The most likely cause is that the bucket policy includes a condition (e.g., aws:SourceIp, aws:SourceVpce, or aws:SecureTransport) that does not match the request context from the EC2 instance. Even though the IAM role grants access, the bucket policy's explicit condition denies the request if the condition key evaluates to false, resulting in an implicit deny. This is a common misconfiguration where the role has permissions but the bucket policy's conditions are too restrictive.
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 bucket policy has a condition that does not match the request context.
Why this is correct
Conditions can cause implicit denies even if the role is allowed.
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 EC2 instance's security group blocks outbound traffic to S3.
Why it's wrong here
Security groups do not apply to S3.
✗
The S3 bucket is in a different AWS account.
Why it's wrong here
The scenario does not mention cross-account.
✗
The instance profile is not attached to the EC2 instance.
Why it's wrong here
The scenario says the instance has the correct instance profile.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often overlook bucket policy conditions and assume that if the IAM role has S3 permissions and the instance profile is attached, access should work, ignoring that bucket policies can impose additional restrictions that override role permissions.
Trap categories for this question
Scenario analysis trap
The scenario does not mention cross-account.
Detailed technical explanation
How to think about this question
Under the hood, when an EC2 instance assumes an IAM role, the instance profile provides temporary credentials via the instance metadata service (IMDS). The S3 bucket policy is evaluated separately from the IAM role policy; both must grant access (allow) and no explicit deny must exist. Conditions in bucket policies can use global condition keys like aws:SourceIp or aws:VpcSourceIp, and if the request does not match, the condition fails, causing the policy to not apply an allow, resulting in an implicit deny. A real-world scenario is when a bucket policy restricts access to a specific VPC endpoint but the EC2 instance is in a different VPC or uses a public endpoint.
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: The bucket policy has a condition that does not match the request context. — The most likely cause is that the bucket policy includes a condition (e.g., aws:SourceIp, aws:SourceVpce, or aws:SecureTransport) that does not match the request context from the EC2 instance. Even though the IAM role grants access, the bucket policy's explicit condition denies the request if the condition key evaluates to false, resulting in an implicit deny. This is a common misconfiguration where the role has permissions but the bucket policy's conditions are too restrictive.
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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Question Discussion
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