This DVA-C02 practice question tests your understanding of security. 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 access to an S3 bucket from an EC2 instance. The bucket policy allows s3:GetObject for the instance's IAM role, but the application is still getting access denied errors. 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 EC2 instance does not have an instance profile associated with the IAM role.
The most likely cause is that the EC2 instance does not have an instance profile associated with the IAM role. Without an instance profile, the IAM role's credentials are not delivered to the instance metadata service, so the AWS SDK cannot assume the role to sign requests to S3. This results in access denied errors even though the bucket policy explicitly allows s3:GetObject for that role.
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 EC2 instance's security group does not allow outbound traffic to S3.
Why it's wrong here
Security groups do not apply to S3; VPC endpoints or NAT gateways are used.
✗
The S3 bucket is encrypted with SSE-KMS and the instance does not have kms:Decrypt permissions.
Why it's wrong here
While KMS permissions could be an issue, the most likely cause based on the scenario is the missing instance profile.
✗
The S3 bucket has a block public access setting enabled.
Why it's wrong here
Block public access affects public access, not access via IAM roles.
✓
The EC2 instance does not have an instance profile associated with the IAM role.
Why this is correct
The IAM role must be attached to the EC2 instance via an instance profile.
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 overlook the requirement to attach an instance profile to the EC2 instance, assuming that creating an IAM role and applying a bucket policy is sufficient, but the instance must be explicitly associated with the role via an instance profile to inherit its permissions.
Trap categories for this question
Scenario analysis trap
While KMS permissions could be an issue, the most likely cause based on the scenario is the missing instance profile.
Detailed technical explanation
How to think about this question
An instance profile is a container for an IAM role that enables the EC2 instance to assume the role and retrieve temporary credentials from the instance metadata service (IMDS) at http://169.254.169.254/latest/meta-data/iam/security-credentials/. Without the instance profile attached to the EC2 instance, the AWS SDK cannot obtain credentials, so requests are sent unsigned or with invalid credentials, leading to 403 Access Denied. This is a common misconfiguration when launching instances via the AWS CLI or SDK without specifying an IAM instance profile.
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 EC2 instance does not have an instance profile associated with the IAM role. — The most likely cause is that the EC2 instance does not have an instance profile associated with the IAM role. Without an instance profile, the IAM role's credentials are not delivered to the instance metadata service, so the AWS SDK cannot assume the role to sign requests to S3. This results in access denied errors even though the bucket policy explicitly allows s3:GetObject for that role.
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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