ANS-C01 Network Implementation Practice Question
A company is designing a VPC with public and private subnets in two Availability Zones. The private subnets host EC2 instances that need to download patches from the internet. The company wants to minimize costs while ensuring high availability. Which solution meets these requirements?
⚠ Common exam trap
Watch out — candidates often choose a single NAT gateway (Option B) thinking it is sufficient for high availability, but AWS explicitly recommends one NAT gateway per AZ for fault tolerance, and the exam expects you to recognize that a single AZ design is not highly available.
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 in each Availability Zone and configure route tables for private subnets to use the NAT gateway in the same AZ.
Deploying a NAT gateway in each Availability Zone ensures high availability by eliminating a single point of failure, while the private subnets in each AZ use the local NAT gateway for outbound internet access. This design meets the requirement for high availability at minimal cost compared to other resilient architectures, as NAT gateways are fully managed and scale automatically.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create a NAT gateway in one public subnet and use a second NAT gateway in a different AZ as a backup, but only route traffic to the primary.
Why it's wrong here
Traffic does not automatically failover; requires manual intervention.
- ✗
Create a NAT gateway in one public subnet and configure route tables for private subnets to use it.
Why it's wrong here
Single point of failure.
- ✗
Launch a NAT instance in one public subnet and configure route tables for private subnets to use it.
Why it's wrong here
NAT instance is not highly available and requires manual failover.
- ✓
Create a NAT gateway in a public subnet in each Availability Zone and configure route tables for private subnets to use the NAT gateway in the same AZ.
Why this is correct
Highly available and cost-effective with proper AZ-level routing.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.