ANS-C01 aws:SourceVpce condition key Practice Question
A company is using AWS CloudFormation to deploy a stack that includes an S3 bucket with a bucket policy that restricts access to a specific VPC endpoint. The stack fails to create, and the error indicates that the bucket policy contains an invalid principal. Which condition key should be used to restrict access to a VPC endpoint in the bucket policy?
⚠ Common exam trap
A common mistake is attempting to use a VPC endpoint ARN or ID as a principal in the policy. However, VPC endpoints are not valid principals. The correct method uses the `aws:SourceVpce` condition key.
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 condition key aws:SourceVpce
To restrict access to a specific VPC endpoint in an S3 bucket policy, you must use the `aws:SourceVpce` condition key in the `Condition` element, not a principal. VPC endpoints cannot be specified as principals in policies. Option A correctly identifies the condition key. Option B (VPC ID) is incorrect because you need the VPC endpoint ID, not the VPC ID. Option C (ARN of the VPC endpoint) is incorrect because ARNs are not used in condition keys for this purpose. Option D (VPC endpoint service) is incorrect because the endpoint service is not used in this condition.
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 condition key aws:SourceVpce
Why this is correct
Correct. `aws:SourceVpce` is a condition key, not a principal, but it is the standard way to restrict access to a specific VPC endpoint in an S3 bucket policy. The question's phrasing is technically imprecise; the correct method uses this condition key in the Condition element.
- ✗
The VPC ID
Why it's wrong here
Incorrect. The VPC ID alone cannot be used to restrict access; you must specify the VPC endpoint ID using the `aws:SourceVpce` condition key.
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The ARN of the VPC endpoint
Why it's wrong here
Incorrect. The ARN of the VPC endpoint is not used as a principal or condition key in S3 bucket policies for this purpose.
- ✗
The VPC endpoint service
Why it's wrong here
Incorrect. A VPC endpoint service is not a principal and is not used in S3 bucket policies to restrict access to a specific endpoint.
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 |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 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 ANS-C01 exam.