- A
Add a route to the internet gateway in the private subnet route tables.
Why wrong: Private subnets cannot have direct IGW routes.
- B
Add a route to the NAT gateway in the public subnet route tables.
Why wrong: Public subnets do not need NAT routes.
- C
Add a route 0.0.0.0/0 pointing to the NAT gateway in the same AZ in each private subnet route table.
Provides high availability and AZ independence.
- D
Add a route 0.0.0.0/0 pointing to a single NAT gateway in both private subnet route tables.
Why wrong: Single point of failure; best practice is one NAT per AZ.
Question 459 of 1,705
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 is using AWS CloudFormation to deploy a VPC with two public subnets and two private subnets across two Availability Zones. The template includes an internet gateway and a NAT gateway in each public subnet. The company needs to ensure that instances in the private subnets can access the internet. Which route table configuration 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
✓
Add a route 0.0.0.0/0 pointing to the NAT gateway in the same AZ in each private subnet route table.
Option C is correct because private subnets require a default route (0.0.0.0/0) pointing to a NAT gateway in the same Availability Zone to ensure internet-bound traffic is source-NATed. This design maintains high availability by avoiding cross-AZ data transfer costs and single points of failure. The NAT gateway must be placed in a public subnet, and the private subnet route table must explicitly direct traffic to it.
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.
- ✗
Add a route to the internet gateway in the private subnet route tables.
Why it's wrong here
Private subnets cannot have direct IGW routes.
- ✗
Add a route to the NAT gateway in the public subnet route tables.
Why it's wrong here
Public subnets do not need NAT routes.
- ✓
Add a route 0.0.0.0/0 pointing to the NAT gateway in the same AZ in each private subnet route table.
Why this is correct
Provides high availability and AZ independence.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Add a route 0.0.0.0/0 pointing to a single NAT gateway in both private subnet route tables.
Why it's wrong here
Single point of failure; best practice is one NAT per AZ.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume a single NAT gateway is sufficient for cost savings, overlooking the high-availability requirement and cross-AZ data transfer costs that AWS explicitly tests in multi-AZ VPC designs.
Detailed technical explanation
How to think about this question
Under the hood, a NAT gateway performs Port Address Translation (PAT) to translate private instance source IPs to its own Elastic IP, using stateful connections tracked by the NAT gateway. In a multi-AZ setup, each NAT gateway is deployed per AZ to ensure that if one AZ fails, the other AZ's private instances retain internet access without relying on cross-AZ traffic, which also avoids additional data transfer charges (AWS charges for cross-AZ data transfer). The route table entry 0.0.0.0/0 with a NAT gateway target is a static route that overrides the local VPC route for all non-local traffic.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a route 0.0.0.0/0 pointing to the NAT gateway in the same AZ in each private subnet route table. — Option C is correct because private subnets require a default route (0.0.0.0/0) pointing to a NAT gateway in the same Availability Zone to ensure internet-bound traffic is source-NATed. This design maintains high availability by avoiding cross-AZ data transfer costs and single points of failure. The NAT gateway must be placed in a public subnet, and the private subnet route table must explicitly direct traffic to it.
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: Jul 4, 2026
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.
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