ANS-C01 Network Implementation Practice Question
A company has a VPC with public and private subnets in multiple Availability Zones. They want to deploy a NAT gateway for outbound internet access for instances in private subnets. Which of the following is the most highly available architecture?
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
✓
Deploy one NAT gateway in each Availability Zone with a route table per AZ that points to the NAT gateway in the same AZ.
For high availability, you should deploy a NAT gateway in each Availability Zone and route traffic from private subnets in each AZ to the NAT gateway in the same AZ. This avoids cross-AZ data transfer costs and ensures that an AZ failure does not affect other AZs. Option A is correct. Options B and C do not provide equal HA. Option D is incorrect because deploying both NAT gateways in the same Availability Zone creates a single point of failure—if that AZ goes down, both gateways fail, so it is not highly available.
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 one NAT gateway in each Availability Zone with a route table per AZ that points to the NAT gateway in the same AZ.
Why this is correct
This provides per-AZ redundancy and avoids cross-AZ dependency.
- ✗
Deploy one NAT gateway in the first Availability Zone and route all private subnet traffic to that NAT gateway.
Why it's wrong here
This creates a single point of failure; if that AZ fails, all private instances lose internet access.
- ✗
Use a single NAT instance in a public subnet with an auto scaling group and health checks.
Why it's wrong here
NAT instances are less reliable and have lower bandwidth than NAT gateways; they also require management.
- ✗
Deploy two NAT gateways in the first Availability Zone and use a single route table pointing to one of them.
Why it's wrong here
Both NAT gateways in the same AZ are still vulnerable to AZ failure.
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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.