This ANS-C01 practice question tests your understanding of network design. 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 has a VPC with public and private subnets. The private subnets need outbound internet access for software updates. Which design will meet this requirement most securely?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deploy a NAT Gateway in a public subnet and add a route to it from the private subnets.
A NAT Gateway deployed in a public subnet with an Elastic IP allows private subnet instances to initiate outbound connections to the internet (e.g., for software updates) while preventing unsolicited inbound connections. The private subnet route table must have a default route (0.0.0.0/0) pointing to the NAT Gateway, which then forwards traffic to the Internet Gateway (IGW) in the public subnet. This design is the most secure because it avoids exposing private instances directly to the internet and uses a managed, highly available service.
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.
✓
Deploy a NAT Gateway in a public subnet and add a route to it from the private subnets.
Why this is correct
NATGateway allows outbound traffic from private subnets while blocking inbound traffic.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add a default route to the IGW from the private subnet route table.
Why it's wrong here
Private subnets with a direct route to IGW are effectively public, not private.
✗
Place the instances in a public subnet with a route to an Internet Gateway (IGW).
Why it's wrong here
This exposes the instances to inbound internet traffic, reducing security.
✗
Deploy a NAT instance in a private subnet and configure routes to it.
Why it's wrong here
NAT instance in private subnet cannot access the internet without a route through a public subnet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that a NAT instance can be placed in a private subnet and still provide outbound internet access, but in reality, a NAT device must reside in a public subnet with a route to an IGW to translate and forward traffic.
Detailed technical explanation
How to think about this question
A NATGateway uses Port Address Translation (PAT) to map private source IPs and ports to its own Elastic IP and ephemeral ports, with a connection tracking table that times out idle flows after approximately 350 seconds (configurable via TCP keepalives). In real-world scenarios, if the NAT Gateway is in a different Availability Zone than the private instances, cross-AZ data transfer costs apply, so it is best practice to deploy one NAT Gateway per AZ for both high availability and cost efficiency. The NAT Gateway automatically handles failover within its AZ and scales up to 45 Gbps, unlike a NAT instance which requires manual scaling and instance management.
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.
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy a NAT Gateway in a public subnet and add a route to it from the private subnets. — A NAT Gateway deployed in a public subnet with an Elastic IP allows private subnet instances to initiate outbound connections to the internet (e.g., for software updates) while preventing unsolicited inbound connections. The private subnet route table must have a default route (0.0.0.0/0) pointing to the NAT Gateway, which then forwards traffic to the Internet Gateway (IGW) in the public subnet. This design is the most secure because it avoids exposing private instances directly to the internet and uses a managed, highly available service.
What should I do if I get this ANS-C01 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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