ANS-C01 Network Design Practice Question

A company has a VPC with CIDR 172.16.0.0/16. They have two subnets: 172.16.1.0/24 (public) and 172.16.2.0/24 (private) in us-west-2a. They have an EC2 instance in the private subnet that needs to access an S3 bucket for log uploads. The company wants to avoid using a NAT Gateway to reduce costs. The S3 bucket is in the same region. Which solution should the network engineer implement?

⚠ Common exam trap

AWS often tests the misconception that an IAM role alone provides network access, but the trap here is that private subnets require a route to S3, and without a NAT Gateway or VPC endpoint, traffic cannot leave the subnet even with correct IAM permissions.

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 from the private subnet to the endpoint.

A VPC Gateway Endpoint for S3 allows private subnet resources to access S3 without traversing the internet or requiring a NAT Gateway. The endpoint uses AWS PrivateLink to route traffic directly to S3 over the AWS network, and you must add a route in the private subnet's route table pointing to the endpoint (prefix list ID) to enable connectivity.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Assign an IAM instance profile to the EC2 instance that allows S3 access.
Why it's wrong here
IAM controls permissions but does not provide network connectivity to S3.
✗
Set up a VPN connection from the VPC to the S3 bucket.
Why it's wrong here
S3 does not support VPN connections; you need an endpoint or internet access.
✓
Create a VPC Gateway Endpoint for S3 and add a route from the private subnet to the endpoint.
Why this is correct
A gateway endpoint provides private connectivity to S3 without a NAT.
✗
Create an S3 access point and configure the VPC to use it.
Why it's wrong here
An S3 access point is a managed endpoint for S3 but still requires network connectivity via a gateway endpoint or NAT.

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

ANS-C01 Network Design Practice Question

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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