Question 301 of 1,546
Networking and Content DeliveryhardMultiple ChoiceObjective-mapped

Quick Answer

The correct solution is to deploy a NAT gateway in a public subnet with an Elastic IP and route outbound traffic from the private subnets through it. This works because the NAT gateway performs source network address translation (SNAT), replacing the private IPs of the web servers with its own static Elastic IP, thereby providing a consistent static outbound IP for EC2 instances using NAT gateway. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of how to combine high-availability architecture with fixed IP requirements for external API whitelisting—a common real-world pattern. A frequent trap is choosing a NAT instance or a proxy fleet, but the NAT gateway is fully managed, scales automatically, and guarantees a single static IP via its Elastic IP association. Memory tip: think “NAT Gateway = Static Outbound IP Gateway” — the Elastic IP is the anchor that never changes, so the API provider sees one consistent source.

SOA-C02 Networking and Content Delivery Practice Question

This SOA-C02 practice question tests your understanding of networking and content delivery. 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. An Application Load Balancer (ALB) is deployed in the public subnets, and an Auto Scaling group of web servers is deployed in the private subnets. The web servers need to frequently make HTTPS requests to an external API. The API provider requires that all requests originate from a consistent set of static IP addresses for whitelisting. The SysOps administrator must ensure that outbound traffic from the web servers has static source IP addresses. Which solution should be implemented?

Question 1hardmultiple 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

Deploy a NAT gateway in a public subnet with an Elastic IP and route outbound traffic from the private subnets through the NAT gateway.

Option B is correct because a NAT gateway placed in a public subnet with an Elastic IP provides a consistent, static source IP for all outbound traffic from instances in private subnets. The web servers route their outbound HTTPS requests through the NAT gateway, which performs source NAT (SNAT) using the Elastic IP, satisfying the API provider's whitelisting requirement. This design keeps the web servers in private subnets for security while ensuring a fixed public IP for outbound traffic.

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.

  • Place the web servers in public subnets and assign each instance an Elastic IP address.

    Why it's wrong here

    This would give static IPs but exposes the instances directly to the internet, increasing the attack surface and going against the requirement for private subnets.

  • Deploy a NAT gateway in a public subnet with an Elastic IP and route outbound traffic from the private subnets through the NAT gateway.

    Why this is correct

    The NAT gateway provides a static Elastic IP for outbound traffic from private instances, fulfilling the requirement securely.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Create a VPC endpoint for the external API service.

    Why it's wrong here

    VPC endpoints are only supported for AWS and some third-party services listed in AWS PrivateLink. Most external APIs do not support VPC endpoints.

  • Use AWS Global Accelerator to provide static IP addresses for outbound traffic.

    Why it's wrong here

    Global Accelerator provides static IPs for inbound traffic to your application, not for outbound traffic from your instances.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates confuse AWS Global Accelerator's static IPs for inbound traffic with the need for static outbound IPs, or mistakenly think VPC endpoints can be used for any external service, when they only work with supported AWS services.

Detailed technical explanation

How to think about this question

Under the hood, a NAT gateway uses port address translation (PAT) to map multiple private IPs to a single Elastic IP, with a connection tracking table that maintains state for each outbound flow. The NAT gateway's Elastic IP is assigned at creation and remains static until explicitly released, ensuring consistent whitelisting. In a real-world scenario, if the API provider changes their whitelist, you only need to update one IP (the NAT gateway's Elastic IP) rather than reconfiguring each instance.

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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.

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.

Related practice questions

Related SOA-C02 practice-question pages

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FAQ

Questions learners often ask

What does this SOA-C02 question test?

Networking and Content Delivery — This question tests Networking and Content Delivery — 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 with an Elastic IP and route outbound traffic from the private subnets through the NAT gateway. — Option B is correct because a NAT gateway placed in a public subnet with an Elastic IP provides a consistent, static source IP for all outbound traffic from instances in private subnets. The web servers route their outbound HTTPS requests through the NAT gateway, which performs source NAT (SNAT) using the Elastic IP, satisfying the API provider's whitelisting requirement. This design keeps the web servers in private subnets for security while ensuring a fixed public IP for outbound traffic.

What should I do if I get this SOA-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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Last reviewed: Jun 11, 2026

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This SOA-C02 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 SOA-C02 exam.