ANS-C01 Network Design Practice Question
A company has a VPC with a CIDR block of 10.0.0.0/16. It has a public subnet (10.0.1.0/24) and a private subnet (10.0.2.0/24). 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 be used?
⚠ Common exam trap
Test-takers frequently confuse Interface Endpoints (powered by AWS PrivateLink) with Gateway Endpoints, assuming S3 supports Interface Endpoints, but S3 only supports Gateway Endpoints (and later, Gateway Load Balancer endpoints, not Interface Endpoints).
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 in the private subnet route table pointing to the endpoint
A VPC Gateway Endpoint for S3 allows private subnet resources to access S3 without traversing the internet, using AWS's internal network. By adding a route in the private subnet's route table pointing to the gateway endpoint (prefix list for S3), traffic destined for S3 stays within the AWS network, meeting the requirement to avoid internet transit.
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 associate it with the private subnet
Why it's wrong here
Interface Endpoint is not supported for S3; S3 uses Gateway Endpoints.
- ✗
Create a NAT Gateway in the public subnet and add a route in the private subnet route table pointing to the NAT Gateway
Why it's wrong here
NAT Gateway uses the internet, not private connectivity.
- ✓
Create a VPC Gateway Endpoint for S3 and add a route in the private subnet route table pointing to the endpoint
Why this is correct
Gateway Endpoint provides private access to S3.
- ✗
Set up an AWS Direct Connect connection and use a private virtual interface
Why it's wrong here
Direct Connect is overkill for in-region S3 access and still requires a VPC endpoint.
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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Same concept, more angles
1 more way this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company has a VPC with a CIDR block of 10.0.0.0/16. They have three subnets: Subnet A (10.0.1.0/24) in us-east-1a, Subnet B (10.0.2.0/24) in us-east-1b, and Subnet C (10.0.3.0/24) in us-east-1c. The company has deployed a set of EC2 instances in Subnet A that need to access an Amazon S3 bucket. The company wants to ensure that traffic to S3 does not traverse the internet and remains within the AWS network. The VPC has a VPC endpoint for S3 (gateway type) created and associated with the route table for Subnet A. However, the instances are unable to access the S3 bucket. What is the MOST likely cause?
medium- A.The VPC does not have an internet gateway attached.
- ✓ B.The route table for Subnet A does not have a route for the S3 prefix list pointing to the VPC endpoint.
- C.The S3 bucket policy does not allow access from the VPC endpoint.
- D.The VPC endpoint is not associated with a security group that allows outbound traffic to S3.
Why B: A gateway VPC endpoint for S3 is only accessible from the subnet whose route table has a route to the endpoint. The route table for Subnet A must have a route for the S3 prefix list pointing to the VPC endpoint. If that route is missing, traffic will not use the endpoint. Option A is incorrect because a VPC endpoint does not require an internet gateway. Option C is incorrect because a gateway endpoint does not use security groups; it uses endpoint policies. Option D is incorrect because the endpoint policy does not need to be explicitly attached to the bucket; the bucket policy must grant access to the VPC endpoint.
JA
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.