ANS-C01 Network Design Practice Question
A solutions architect is designing a VPC with public and private subnets. The application in the private subnet needs to download patches from the internet. Which TWO options allow outbound internet access while keeping the EC2 instance in the private subnet without a public IP address?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that a NAT Gateway requires a public IP on the private instance, but in reality, the NAT Gateway itself has the public IP and performs SNAT, so the private instance never needs a public IP.
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 endpoint for Amazon S3 and update the route table.
A VPC endpoint for Amazon S3 allows private subnet instances to access S3 buckets (where patches can be stored) without traversing the internet, using the AWS network backbone. This keeps the EC2 instance private (no public IP) while enabling outbound access to a specific AWS service. Option E is correct because a NAT Gateway in a public subnet provides source network address translation (SNAT) for private instances, translating their private IPs to the NAT Gateway's Elastic IP for outbound internet traffic, while the private instance itself remains without a public IP.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Attach an Internet Gateway to the VPC and assign a public IP to the instance.
Why it's wrong here
This would give the instance a public IP, which is not desired.
- ✗
Set up a Direct Connect connection to an on-premises data center.
Why it's wrong here
Direct Connect is for private connectivity, not general internet access.
- ✓
Create a VPC endpoint for Amazon S3 and update the route table.
Why this is correct
VPC endpoint allows private access to S3 without internet.
- ✗
Establish a VPN connection to a third-party proxy service.
Why it's wrong here
VPN is not typically used for outbound internet patches; it adds complexity.
- ✓
Deploy a NAT Gateway in a public subnet and update the private subnet route table to point 0.0.0.0/0 to the NAT Gateway.
Why this is correct
A NAT Gateway deployed in a public subnet with an Elastic IP translates private subnet traffic to the internet, allowing outbound patch downloads while preventing any inbound connection to the EC2 instance. This satisfies the constraint that the instance must remain without a public IP address, as the NAT Gateway handles source network address translation (SNAT) for the private subnet’s default route (0.0.0.0/0).
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 |
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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 is deploying a multi-tier web application in a VPC. The architecture includes an internet-facing Application Load Balancer (ALB) in public subnets, a fleet of EC2 instances in private subnets, and an Amazon RDS database in a separate private subnet. The security team requires that the web application logs be stored in an Amazon S3 bucket for compliance. The EC2 instances have an instance profile that grants write access to the S3 bucket. The EC2 instances are in a private subnet that does not have a route to the internet. The company wants to ensure that the EC2 instances can upload logs to the S3 bucket without traversing the internet. Which solution should they implement?
medium- ✓ A.Create a VPC Gateway Endpoint for S3 and add a route in the private subnet's route table pointing to the endpoint
- B.Create a VPC Interface Endpoint for S3
- C.Deploy a forward proxy server in a public subnet and configure the EC2 instances to use it
- D.Attach a NAT Gateway to the private subnet and configure a route to the NAT Gateway
Why A: A VPC Gateway Endpoint for S3 allows EC2 instances in private subnets to access S3 over the AWS network without traversing the internet. Since the instances have an instance profile granting write access, adding a route in the private subnet's route table pointing to the gateway endpoint enables direct, private connectivity to S3. This meets the security requirement of keeping traffic within the AWS backbone.
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.