← SOA-C02·Amazon Web Services

Question 119 of 1,546

Networking and Content Delivery →hardMultiple ChoiceObjective-mapped

SOA-C02 Networking and Content Delivery Practice Question

This SOA-C02 practice question tests your understanding of networking and content delivery. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 a public subnet and a private subnet. An Amazon EC2 instance in the private subnet needs to download security patches from the internet, but the instance must not be directly accessible from the internet. The SysOps administrator configured a NAT gateway in the public subnet and added a route in the private subnet's route table pointing 0.0.0.0/0 to the NAT gateway. The instance's security group allows all outbound traffic. However, the instance still cannot reach the internet. What is the most likely missing configuration?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Read the full NAT/PAT explanation →

A
Attach an Elastic IP to the NAT gateway
Why wrong: An Elastic IP must be assigned when creating a NAT gateway. If it was created without one, it would have failed. Assuming the NAT gateway exists, an EIP is already attached.
B
Enable DNS resolution in the VPC
Why wrong: DNS resolution is not required for internet access via NAT gateway; it is used for resolving DNS names.
C
Add a route in the public subnet's route table that directs 0.0.0.0/0 traffic to an internet gateway
The NAT gateway resides in the public subnet; that subnet's route table must have a route to an internet gateway for the NAT gateway to reach the internet.
D
Modify the network ACL of the private subnet to allow inbound ephemeral ports from the NAT gateway's private IP
Why wrong: By default, network ACLs allow all inbound/outbound traffic. If they have not been modified, they are not blocking traffic. This is rarely the cause.

Full breakdown with real-world context →

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

✓

Add a route in the public subnet's route table that directs 0.0.0.0/0 traffic to an internet gateway

The NAT gateway is in the public subnet, but for it to route traffic to the internet, the public subnet must have a route table entry that directs 0.0.0.0/0 traffic to an internet gateway (IGW). Without this route, the NAT gateway cannot forward outbound traffic to the IGW, so the private instance's traffic is dropped. Option C correctly identifies this missing route.

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.

✗
Attach an Elastic IP to the NAT gateway
Why it's wrong here
An Elastic IP must be assigned when creating a NAT gateway. If it was created without one, it would have failed. Assuming the NAT gateway exists, an EIP is already attached.
✗
Enable DNS resolution in the VPC
Why it's wrong here
DNS resolution is not required for internet access via NAT gateway; it is used for resolving DNS names.
✓
Add a route in the public subnet's route table that directs 0.0.0.0/0 traffic to an internet gateway
Why this is correct
The NAT gateway resides in the public subnet; that subnet's route table must have a route to an internet gateway for the NAT gateway to reach the internet.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Modify the network ACL of the private subnet to allow inbound ephemeral ports from the NAT gateway's private IP
Why it's wrong here
By default, network ACLs allow all inbound/outbound traffic. If they have not been modified, they are not blocking traffic. This is rarely the cause.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume configuring the private subnet's route table to point to the NAT gateway is sufficient, forgetting that the NAT gateway itself needs a route to the internet via an internet gateway in its own subnet.

Detailed technical explanation

How to think about this question

A NAT gateway in a public subnet requires an internet gateway as the next hop for 0.0.0.0/0 traffic; the NAT gateway translates the private instance's source IP to its own Elastic IP and forwards packets to the IGW. Without the IGW route in the public subnet's route table, the NAT gateway has no path to the internet, causing packets to be dropped silently. This is a common misconfiguration because administrators often focus on the private subnet's route table and overlook the public subnet's routing.

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.

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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: Add a route in the public subnet's route table that directs 0.0.0.0/0 traffic to an internet gateway — The NAT gateway is in the public subnet, but for it to route traffic to the internet, the public subnet must have a route table entry that directs 0.0.0.0/0 traffic to an internet gateway (IGW). Without this route, the NAT gateway cannot forward outbound traffic to the IGW, so the private instance's traffic is dropped. Option C correctly identifies this missing route.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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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.