ANS-C01 Network Implementation Practice Question
A company has a VPC with a public subnet and a private subnet. An EC2 instance in the private subnet needs to access an S3 bucket. The company wants to ensure that traffic to S3 does not traverse the internet. Which solution should a network engineer implement?
⚠ Common exam trap
The ANS-C01 exam often tests the distinction between gateway endpoints and interface endpoints for AWS services, and the trap here is that candidates may incorrectly assume S3 supports interface endpoints (like it does for other services such as DynamoDB or API Gateway) or that a NAT gateway is required for private subnet outbound traffic, when a gateway endpoint is the correct and more efficient choice for S3.
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
✓
Create a VPC gateway endpoint for S3 and add a route to the S3 prefix list via the endpoint.
A VPC gateway endpoint for S3 allows instances in a private subnet to access S3 privately using AWS's internal network, without traversing the internet. By adding a route to the S3 prefix list via the gateway endpoint, traffic destined for S3 is directed through the endpoint, which uses AWS's private backbone. This solution is cost-effective and does not require a NAT gateway or internet gateway.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a VPC interface endpoint for S3 and attach it to the private subnet.
Why it's wrong here
S3 does not support interface endpoints; only gateway endpoints.
- ✗
Deploy an S3 VPN endpoint in the VPC.
Why it's wrong here
No such service; VPN endpoints are for other services.
- ✓
Create a VPC gateway endpoint for S3 and add a route to the S3 prefix list via the endpoint.
Why this is correct
Gateway endpoints provide private connectivity to S3.
- ✗
Set up a NAT gateway in the public subnet and add a route to the S3 prefix list via the NAT gateway.
Why it's wrong here
Traffic would go through the NAT gateway and internet, not private.
Visual reference
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.