The answer is a NAT Gateway in a public subnet combined with a route table in the private subnet that has a default route (0.0.0.0/0) pointing to that NAT Gateway. This works because the NAT Gateway, residing in a public subnet with an Internet Gateway, translates the private IPs of the EC2 instances to its own Elastic IP for outbound traffic, while the route table ensures all internet-bound packets from the private instances are forwarded to the NAT Gateway. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how to enable private EC2 instances internet access without exposing them to inbound connections, often appearing in questions about VPC design for secure web applications. A common trap is confusing a NAT Gateway with a NAT Instance or forgetting that the route table must explicitly point 0.0.0.0/0 to the NAT Gateway, not the Internet Gateway. Memory tip: think “Private out, NAT about” — private subnets route to NAT, NAT routes to IGW.
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is designing a new VPC for a web application that must be accessible from the internet. The application will run on EC2 instances in private subnets. Which TWO components are required to allow the EC2 instances to access the internet for updates?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A route table in the private subnet with a default route pointing to the NAT Gateway
Option A is correct because a route table in the private subnet with a default route (0.0.0.0/0) pointing to a NAT Gateway is required to direct outbound internet traffic from the EC2 instances to the NAT Gateway. The NAT Gateway then forwards this traffic to the Internet Gateway, enabling the instances to download updates while remaining inaccessible from the internet.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
A route table in the private subnet with a default route pointing to the NAT Gateway
Why this is correct
The route table directs traffic to the NATGateway.
Related concept
Read the scenario before looking for a memorised answer.
✗
An Internet Gateway attached to the VPC
Why it's wrong here
Internet Gateway is for public subnets, not for private subnets directly.
✓
A NAT Gateway in a public subnet
Why this is correct
NATGateway allows private instances to access the internet.
Related concept
Read the scenario before looking for a memorised answer.
✗
VPC Flow Logs
Why it's wrong here
Flow Logs capture traffic metadata, not provide connectivity.
✗
A virtual private gateway
Why it's wrong here
Virtual private gateway is for VPN connections, not internet access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume an Internet Gateway alone suffices for all internet access, forgetting that instances in private subnets require a NAT device (NAT Gateway or NAT Instance) to translate their private IPs for outbound traffic.
Detailed technical explanation
How to think about this question
A NATGateway operates at the network layer (Layer 3) and performs source network address translation (SNAT), replacing the private IP of the EC2 instance with the NAT Gateway's Elastic IP for outbound traffic. The NAT Gateway must be placed in a public subnet with an Internet Gateway route, and the private subnet's route table must have a 0.0.0.0/0 route pointing to the NAT Gateway's ID. This design ensures that return traffic is correctly forwarded back to the private instance, as the NAT Gateway maintains stateful connection tracking.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A route table in the private subnet with a default route pointing to the NAT Gateway — Option A is correct because a route table in the private subnet with a default route (0.0.0.0/0) pointing to a NAT Gateway is required to direct outbound internet traffic from the EC2 instances to the NAT Gateway. The NAT Gateway then forwards this traffic to the Internet Gateway, enabling the instances to download updates while remaining inaccessible from the internet.
What should I do if I get this SAP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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