SCS-C02 Data Protection Practice Question
A security engineer is troubleshooting an issue where an EC2 instance cannot access an S3 bucket via a VPC endpoint. The bucket policy allows access only from the VPC endpoint. The instance has an IAM role that grants s3:GetObject on the bucket. The EC2 instance receives an AccessDenied error. What is the most likely cause?
Answer choices
Why each option matters
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 does not include the aws:SourceVpce condition.
The AccessDenied error occurs because the S3 bucket policy must include the aws:SourceVpce condition to allow access from the specific VPC endpoint. Without this condition, the bucket policy denies all requests that do not originate from the endpoint, regardless of IAM permissions. Option B is correct because the missing condition is the most likely cause.
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 does not have sufficient permissions.
Why it's wrong here
The role grants s3:GetObject, so permissions should be sufficient from IAM side.
- ✓
The bucket policy does not include the aws:SourceVpce condition.
Why this is correct
Without this condition, the bucket policy that restricts to VPC endpoint may not match the request, causing AccessDenied.
- ✗
The VPC endpoint policy is blocking the request.
Why it's wrong here
Endpoint policy could block, but the problem statement says bucket policy allows only from VPC endpoint; the endpoint policy might not be the issue.
- ✗
The EC2 instance's security group does not allow outbound traffic to S3.
Why it's wrong here
Security group would cause a timeout, not an AccessDenied error from S3.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SCS-C02 exam.