SAA-C03 Design Secure Architectures Practice Question
A company runs EC2 instances in private subnets and needs to access Amazon S3 objects without using a NAT gateway. They want the traffic to stay within AWS private networking as much as possible (no internet egress). Which VPC endpoint type should they create for Amazon S3?
⚠ Common exam trap
Watch out — candidates often confuse Gateway endpoints (for S3/DynamoDB) with Interface endpoints (for other AWS services), or incorrectly assume that a NAT gateway is required for private subnet egress, missing that Gateway endpoints provide a free, private alternative for S3 access.
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 Gateway VPC endpoint for S3 and update the route tables to use it
A Gateway VPC endpoint for S3 is the correct choice because it uses prefix lists and route table entries to send S3 traffic directly through AWS's private network without leaving the AWS backbone or requiring a NAT gateway. This endpoint type supports S3 and DynamoDB only, and it does not incur hourly charges, making it cost-effective for private subnet instances to access S3 objects securely.
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 an Interface VPC endpoint for S3 and point the instances to it
Why it's wrong here
Interface VPC endpoints (powered by AWS PrivateLink) use elastic network interfaces (ENIs) in your subnets and are supported for many services, but Amazon S3 is a special case. For S3, the supported private connectivity model is a Gateway VPC endpoint that integrates with route tables, not an interface endpoint.
- ✓
Create a Gateway VPC endpoint for S3 and update the route tables to use it
Why this is correct
Gateway VPC endpoints for S3 are the supported way to send S3 traffic from private subnets without NAT. They add routes in the relevant route tables (via S3 prefix lists) so requests to S3 go through the AWS network. This avoids internet egress and keeps the path private to the extent intended by VPC endpoint routing.
- ✗
Create a NAT gateway and allow outbound HTTPS to S3
Why it's wrong here
A NAT gateway provides outbound internet connectivity. Even if the destination is S3 over HTTPS, traffic still traverses the NAT gateway and leaves the VPC via the internet path, which violates the requirement to avoid NAT/internet egress.
- ✗
Create a VPC endpoint service and manually register S3 as a provider endpoint
Why it's wrong here
VPC Endpoint Services are for exposing your own services privately (or consuming privately exposed endpoint services). S3 is not registered as a provider endpoint service by customers. The correct AWS-managed approach for S3 is a Gateway 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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About these practice questions
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAA-C03 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 SAA-C03 exam.