Question 43 of 1,705
Network DesignmediumMultiple ChoiceObjective-mapped

Quick Answer

The correct answer is to create a centralized egress VPC with a NAT Gateway in each Availability Zone, peer the application VPCs to it, and route 0.0.0.0/0 traffic through a firewall appliance. This solution meets the requirements for logging and inspection because the centralized egress VPC architecture forces all outbound internet traffic through a firewall appliance for inspection, while deploying a NAT Gateway per AZ ensures high availability by eliminating any single point of failure. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of combining centralized inspection with resilient egress—a common trap is choosing a single NAT Gateway or a single firewall instance, which fails the availability requirement. Remember that for inspection, you need a stateful firewall in the traffic path, but for availability, you need a NAT Gateway in every AZ. Memory tip: “Inspect with a firewall, survive with a NAT per AZ.”

ANS-C01 Network Design Practice Question

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 in three Availability Zones. They have EC2 instances in private subnets that need to download patches from the internet. The company requires that all outbound traffic to the internet is logged and inspected. Which solution meets these requirements with the highest availability?

Question 1mediummultiple choice
Read the full NAT/PAT explanation →

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 centralized egress VPC with a NAT Gateway in each AZ. Peer the application VPCs to the egress VPC and route 0.0.0.0/0 traffic through a firewall appliance in the egress VPC.

Option D is correct because it meets the requirements for logging and inspecting all outbound internet traffic by routing it through a centralized firewall appliance in an egress VPC, while also providing high availability through NAT Gateways deployed in each Availability Zone. This architecture ensures that traffic is inspected before reaching the internet, and the use of multiple NAT Gateways eliminates single points of failure, achieving the highest availability compared to single-instance or single-gateway solutions.

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.

  • Launch a NAT instance in one public subnet and configure all private subnet route tables to send 0.0.0.0/0 to the NAT instance.

    Why it's wrong here

    A single NAT instance is a single point of failure and requires manual failover.

  • Place a single NAT Gateway in one public subnet and configure all private subnet route tables to send 0.0.0.0/0 to that NAT Gateway.

    Why it's wrong here

    A single NAT Gateway is a single point of failure; if its AZ goes down, all outbound traffic fails.

  • Attach an internet gateway to the VPC and add a route in the private subnet route tables to send 0.0.0.0/0 to the internet gateway.

    Why it's wrong here

    Internet gateways do not provide logging or inspection; instances in private subnets need a NAT device.

  • Create a centralized egress VPC with a NAT Gateway in each AZ. Peer the application VPCs to the egress VPC and route 0.0.0.0/0 traffic through a firewall appliance in the egress VPC.

    Why this is correct

    NAT Gateways in each AZ provide high availability, and centralized inspection allows logging.

    Related concept

    Read the scenario before looking for a memorised answer.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often assume a single NAT Gateway or NAT instance provides sufficient availability and inspection, overlooking the requirement for logging and inspection, which necessitates a firewall or inspection appliance, and the need for multi-AZ deployment to achieve high availability.

Detailed technical explanation

How to think about this question

In a centralized egress VPC model, traffic from application VPCs is routed via VPC peering or Transit Gateway to the egress VPC, where a firewall appliance (e.g., AWS Network Firewall, third-party NGFW) performs deep packet inspection and logging. NAT Gateways in each AZ provide highly available source network address translation (SNAT) for outbound traffic, ensuring that return traffic is correctly routed back through the firewall. This design aligns with AWS best practices for centralized inspection and meets compliance requirements for logging all outbound traffic, as the firewall can capture full flow logs or application-layer data.

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

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

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.

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FAQ

Questions learners often ask

What does this ANS-C01 question test?

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: Create a centralized egress VPC with a NAT Gateway in each AZ. Peer the application VPCs to the egress VPC and route 0.0.0.0/0 traffic through a firewall appliance in the egress VPC. — Option D is correct because it meets the requirements for logging and inspecting all outbound internet traffic by routing it through a centralized firewall appliance in an egress VPC, while also providing high availability through NAT Gateways deployed in each Availability Zone. This architecture ensures that traffic is inspected before reaching the internet, and the use of multiple NAT Gateways eliminates single points of failure, achieving the highest availability compared to single-instance or single-gateway solutions.

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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Last reviewed: Jun 24, 2026

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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.