Question 384 of 1,024
Cloud Technology and ServicesmediumMultiple ChoiceObjective-mapped

AWS NAT Gateway: Enable Outbound Traffic Without Inbound Access

This CLF-C02 practice question tests your understanding of cloud technology and services. 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 runs database servers in private subnets with no direct internet access for security. However, these servers need to download OS updates from the internet. Which VPC component allows the private instances to make outbound internet connections while remaining unreachable from the internet?

Quick Answer

The answer is the NAT Gateway. This is correct because a NAT Gateway allows instances in a private subnet to initiate outbound IPv4 traffic to the internet—such as downloading OS updates—while using Source Network Address Translation (SNAT) to replace the private source IP with the gateway’s public Elastic IP, ensuring response traffic can return without ever exposing the private instances to inbound connections from the internet. On the AWS Certified Cloud Practitioner CLF-C02 exam, this scenario tests your understanding of how to securely enable outbound-only internet access, often appearing as a direct comparison to an Internet Gateway, which would expose instances to inbound traffic. A common trap is confusing the two: remember that an Internet Gateway allows bidirectional traffic for public subnets, while a NAT Gateway is strictly for outbound traffic from private subnets. For a quick memory tip, think “NAT = No Access To” the private instances from the internet.

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

NAT Gateway

A NAT Gateway enables instances in a private subnet to initiate outbound IPv4 traffic to the internet (e.g., for OS updates) while preventing the internet from initiating inbound connections to those instances. It resides in a public subnet with an Elastic IP and uses Source Network Address Translation (SNAT) to replace the private source IP with the gateway's public IP, making the response traffic routable back without exposing the private instances.

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.

  • Internet Gateway

    Why it's wrong here

    An Internet Gateway enables two-way internet communication for instances with public IPs. Private subnet instances do not have public IPs and should not be directly reachable from the internet.

  • NAT Gateway

    Why this is correct

    A NAT Gateway placed in a public subnet translates private instance IP addresses for outbound internet traffic. Return traffic is allowed back through the NAT, but no inbound connections initiated from the internet can reach the private instances.

    Related concept

    Read the scenario before looking for a memorised answer.

  • VPN Gateway

    Why it's wrong here

    A VPN Gateway connects the VPC to an on-premises network over an encrypted VPN tunnel. It does not provide internet access for private subnet instances.

  • VPC Endpoint

    Why it's wrong here

    VPC Endpoints provide private connectivity to AWS services without requiring internet access. They do not provide internet access for downloading OS updates from public repositories.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates confuse a NAT Gateway with an Internet Gateway, assuming both provide internet access, but the key differentiator is that a NAT Gateway only allows outbound-initiated traffic and blocks unsolicited inbound connections, which is exactly what the question requires.

Detailed technical explanation

How to think about this question

Under the hood, the NAT Gateway performs port address translation (PAT) on outbound packets, mapping many private IPs to a single public IP and tracking state in a connection table. A subtle behavior is that NAT Gateways do not support IPv6 traffic (for IPv6, an egress-only Internet Gateway is used), and they are zone-resilient only within a single Availability Zone unless you deploy one per AZ. In a real-world scenario, if the OS update servers require HTTPS, the NAT Gateway transparently forwards TCP/443 traffic without decryption, maintaining end-to-end encryption.

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.

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

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FAQ

Questions learners often ask

What does this CLF-C02 question test?

Cloud Technology and Services — This question tests Cloud Technology and Services — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: NAT Gateway — A NAT Gateway enables instances in a private subnet to initiate outbound IPv4 traffic to the internet (e.g., for OS updates) while preventing the internet from initiating inbound connections to those instances. It resides in a public subnet with an Elastic IP and uses Source Network Address Translation (SNAT) to replace the private source IP with the gateway's public IP, making the response traffic routable back without exposing the private instances.

What should I do if I get this CLF-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 CLF-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 CLF-C02 exam.