Question 922 of 1,705
Network Security, Compliance and GovernancehardMultiple ChoiceObjective-mapped

Single Elastic IP for Outbound Traffic — NAT Gateway IP Assignment

This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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. A key principle to apply: nAT instance. 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 a public subnet and a private subnet. An EC2 instance in the private subnet needs to initiate outbound connections to the internet for software updates. The company wants to ensure that all outbound traffic goes through a single, highly available IP address for whitelisting purposes. Which solution should be used?

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

Launch a NAT instance in a public subnet and assign an Elastic IP. Configure the private subnet route table to point to the NAT instance.

A NAT instance in a public subnet with an Elastic IP provides a single, stable IP address for outbound traffic from the private subnet. By configuring the private subnet route table to point to the NAT instance, all outbound internet traffic goes through that instance. While not inherently highly available across Availability Zones, the solution meets the core requirement of a single IP for whitelisting and can be made more resilient using Auto Scaling and instance recovery.

Key principle: NAT instance

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 a public subnet and assign an Elastic IP. Configure the private subnet route table to point to the NAT instance.

    Why this is correct

    Correct. A NAT instance with an Elastic IP provides a single IP for outbound traffic. It can be placed in a public subnet and configured as a route target for the private subnet, allowing instances to initiate outbound connections to the internet.

    Related concept

    NAT instance

  • Create an internet gateway and attach it to the private subnet, then configure the route table.

    Why it's wrong here

    Incorrect. An internet gateway is attached to the VPC, not to a subnet. A private subnet cannot have a direct route to an internet gateway; routes to the internet gateway are only used for public subnets.

  • Create a VPC endpoint for Amazon S3 and route software update traffic through that endpoint.

    Why it's wrong here

    Incorrect. A VPC endpoint for Amazon S3 provides private connectivity to S3 only. Software updates often come from external repositories (e.g., yum, apt) that are not on S3, so this does not meet the general internet access requirement.

  • Create a NAT gateway in each Availability Zone and assign the same Elastic IP to both.

    Why it's wrong here

    Incorrect. Each NAT gateway requires a unique Elastic IP; you cannot assign the same Elastic IP to multiple NAT gateways. Therefore, this configuration is not supported.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The question asks for a 'single, highly available IP address' for whitelisting. While NAT gateways offer high availability, they do not support sharing the same Elastic IP across multiple gateways. A NAT instance, though not fully highly available by default, can still serve as a single IP solution and may be improved with Auto Scaling.

Detailed technical explanation

How to think about this question

Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.

KKey Concepts to Remember

  • NAT instance
  • Elastic IP
  • Private subnet route table
  • High availability

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

NAT instance

Real-world example

How this comes up in practice

A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.

Visual reference

Inside (Private) PC-A 10.0.0.1 PC-B 10.0.0.2 NAT Router Outside (Public) 203.0.113.1 Inside Global Server PAT: many private IPs share one public IP via unique port numbers

What to study next

Got this wrong? Here's your next step.

Review nAT instance, then practise related ANS-C01 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this ANS-C01 question test?

Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — NAT instance.

What is the correct answer to this question?

The correct answer is: Launch a NAT instance in a public subnet and assign an Elastic IP. Configure the private subnet route table to point to the NAT instance. — A NAT instance in a public subnet with an Elastic IP provides a single, stable IP address for outbound traffic from the private subnet. By configuring the private subnet route table to point to the NAT instance, all outbound internet traffic goes through that instance. While not inherently highly available across Availability Zones, the solution meets the core requirement of a single IP for whitelisting and can be made more resilient using Auto Scaling and instance recovery.

What should I do if I get this ANS-C01 question wrong?

Review nAT instance, then practise related ANS-C01 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

NAT instance

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Last reviewed: Jun 7, 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.