- A
Deploy a single EC2 instance configured as a NAT instance in a public subnet.
Why wrong: A single NAT instance is not highly available.
- B
Configure a fleet of proxy servers in an Auto Scaling group with a Network Load Balancer.
Why wrong: Proxy fleet adds complexity and does not guarantee a single IP.
- C
Create a NAT gateway in a public subnet and route traffic from private subnets to it.
NAT gateway is managed, highly available, and provides a single Elastic IP.
- D
Use a VPC endpoint for Amazon S3 to access software updates.
Why wrong: VPC endpoints do not provide general internet access.
Question 888 of 1,705
Single Outbound IP with NAT Gateway — High Availability | AWS Advanced Networking Specialty Explained
This ANS-C01 practice question tests your understanding of network design. 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. The private subnets need outbound internet access for software updates. The company wants to ensure that traffic from private subnets uses a single, highly available IP address for outbound traffic. Which solution meets these requirements?
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
✓
Create a NAT gateway in a public subnet and route traffic from private subnets to it.
Option C is correct because a NAT gateway provides managed, highly available outbound internet access for private subnets using a single elastic IP address. It is deployed in a public subnet and automatically handles failover within an Availability Zone, meeting the requirement for a single, highly available 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.
- ✗
Deploy a single EC2 instance configured as a NAT instance in a public subnet.
Why it's wrong here
A single NAT instance is not highly available.
- ✗
Configure a fleet of proxy servers in an Auto Scaling group with a Network Load Balancer.
Why it's wrong here
Proxy fleet adds complexity and does not guarantee a single IP.
- ✓
Create a NAT gateway in a public subnet and route traffic from private subnets to it.
- ✗
Use a VPC endpoint for Amazon S3 to access software updates.
Why it's wrong here
VPC endpoints do not provide general internet access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The ANS-C01 exam often tests the misconception that a single NAT instance or a proxy fleet with an NLB can provide both high availability and a single outbound IP, but the trap here is that a NAT gateway is the only managed service that inherently combines high availability with a single elastic IP for outbound traffic without additional configuration.
Detailed technical explanation
How to think about this question
A NAT gateway uses Source Network Address Translation (SNAT) to map private IPs to its elastic IP address, and it is horizontally scalable within an Availability Zone, supporting up to 45 Gbps of bandwidth. For cross-AZ high availability, you must deploy a NAT gateway in each AZ and route traffic accordingly, as a single NAT gateway does not automatically fail over to another AZ. In real-world scenarios, this design is critical for workloads like EC2 instances in private subnets that need to access public repositories (e.g., yum, apt) while maintaining a consistent source IP for security logging or whitelisting.
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 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
What to study next
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a NAT gateway in a public subnet and route traffic from private subnets to it. — Option C is correct because a NAT gateway provides managed, highly available outbound internet access for private subnets using a single elastic IP address. It is deployed in a public subnet and automatically handles failover within an Availability Zone, meeting the requirement for a single, highly available IP for outbound traffic.
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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