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.
Network Topology
An EC2 instance is running with an IAM instance profile. The application on the instance is trying to access an S3 bucket, but receives 'Access Denied'. The instance profile has a role with a policy that allows s3:GetObject on the bucket. What is a likely cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The instance is in a private subnet without a VPC endpoint for S3.
Option D is correct because when an EC2 instance is in a private subnet, it cannot reach the S3 public endpoint over the internet. Without a VPC endpoint (gateway or interface type) for S3, traffic to S3 is routed through a NAT device or internet gateway, which may be blocked by network ACLs or route tables. The 'Access Denied' error here is not due to IAM permissions but due to the network path being unavailable, causing the SDK to fail with a connectivity-related denial.
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 instance profile is not attached to the instance.
Why it's wrong here
The CLI output shows the instance profile is attached.
✗
The IAM role does not have the correct permissions.
Why it's wrong here
The policy allows s3:GetObject.
✗
The trust policy of the IAM role does not allow the EC2 service.
Why it's wrong here
For EC2 to assume the role, the trust policy must allow ec2.amazonaws.com; if it were missing, the instance would not have credentials.
✓
The instance is in a private subnet without a VPC endpoint for S3.
Why this is correct
Without a VPC endpoint or NATgateway, the instance cannot reach S3.
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 assume all 'Access Denied' errors are due to IAM permissions, but network-level restrictions (like missing VPC endpoints or incorrect route tables) can produce the same error message from the AWS SDK.
Trap categories for this question
Command / output trap
The CLI output shows the instance profile is attached.
Detailed technical explanation
How to think about this question
When an EC2 instance in a private subnet attempts to access S3, the default route (0.0.0.0/0) points to a NAT gateway or instance, which requires internet access. Without a VPC gateway endpoint for S3, DNS resolution of the S3 endpoint returns public IPs that are unreachable from the private subnet, causing the SDK to throw an 'Access Denied' error (often indistinguishable from a permissions error). A VPC gateway endpoint uses prefix lists in the route table to direct S3 traffic through the AWS network, bypassing the internet.
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 instance is in a private subnet without a VPC endpoint for S3. — Option D is correct because when an EC2 instance is in a private subnet, it cannot reach the S3 public endpoint over the internet. Without a VPC endpoint (gateway or interface type) for S3, traffic to S3 is routed through a NAT device or internet gateway, which may be blocked by network ACLs or route tables. The 'Access Denied' error here is not due to IAM permissions but due to the network path being unavailable, causing the SDK to fail with a connectivity-related denial.
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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