The answer is that the EC2 instance does not have an instance profile associated with the IAM role, which directly causes the access denied errors. An IAM role alone is not enough; it must be attached to an EC2 instance through an instance profile, which acts as a container that enables the instance to retrieve temporary credentials from AWS STS. Without this profile, the application cannot sign API requests to S3, even if the role’s trust and permissions policies are perfectly configured. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding that an instance profile is a mandatory intermediary—a common trap is assuming a role’s policy is sufficient. Remember: a role is just a set of permissions; the instance profile is the bridge that lets the EC2 instance assume it. Memory tip: think “profile before permission”—the instance profile must exist and be attached before the role’s policies can take effect.
DVA-C02 Security Practice Question
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 company uses an IAM role to allow an EC2 instance to access an S3 bucket. The role's trust policy allows the EC2 service, and the permissions policy grants s3:GetObject on the bucket. The application on the instance receives 'Access Denied' errors when trying to read objects. 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. An IAM role must be attached to an EC2 instance via an instance profile, which acts as a container for the role. Without this association, the instance cannot obtain temporary credentials from the AWS Security Token Service (STS) to sign API requests, resulting in 'Access Denied' errors even if the role's trust and permissions policies are correctly configured.
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 role's trust policy does not allow the EC2 service.
Why it's wrong here
The trust policy allows EC2 service, but the issue is that the instance does not have a profile.
✗
The S3 bucket has default encryption enabled.
Why it's wrong here
Default encryption does not block access; it encrypts objects at rest.
✓
The EC2 instance does not have an instance profile associated with the IAM role.
Why this is correct
Without an instance profile, the instance cannot assume the role and retrieve temporary credentials.
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 S3 bucket policy explicitly denies s3:GetObject.
Why it's wrong here
The bucket policy would override the role permission, but the question states the role grants access, so no explicit deny is mentioned.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the IAM role's trust and permissions policies are sufficient, overlooking the mandatory instance profile association required for EC2 to use the role.
Detailed technical explanation
How to think about this question
An instance profile is a container for an IAM role that is used to pass role information to an EC2 instance at launch time. When the instance calls the AWS credentials endpoint (169.254.169.254/latest/meta-data/iam/security-credentials/), it retrieves temporary credentials only if the instance profile is attached. Without this attachment, the AWS SDK or CLI on the instance cannot sign requests, leading to 'Access Denied' even if the role's policies are correct. In practice, this is a common misconfiguration when roles are created but not associated with the instance via the 'aws ec2 associate-iam-instance-profile' command or the AWS Management Console.
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. An IAM role must be attached to an EC2 instance via an instance profile, which acts as a container for the role. Without this association, the instance cannot obtain temporary credentials from the AWS Security Token Service (STS) to sign API requests, resulting in 'Access Denied' errors even if the role's trust and permissions policies are correctly configured.
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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