ANS-C01 Network Design Practice Question
A startup wants to design a cost-effective network for a new application. They expect low traffic initially but need to handle sudden spikes. They plan to use Amazon EC2 instances behind an Application Load Balancer (ALB) in a single VPC. The application must be highly available within the region. The network engineer has proposed using two public subnets in two Availability Zones for the ALB, and two private subnets for the EC2 instances. The EC2 instances need to access the internet for updates. What is the MOST cost-effective and highly available design?
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
✓
Use a NAT gateway in each public subnet (one per AZ)
Using a NAT gateway in each Availability Zone provides high availability because each AZ has its own NAT gateway, eliminating a single point of failure. NAT gateways are managed by AWS, reducing operational overhead compared to NAT instances. Option A is wrong because a single NAT instance is a single point of failure. Option C is wrong because while NAT instances per AZ provide high availability, they require manual management and are less cost-effective than using managed NAT gateways. Option D is wrong because a single NAT gateway is a single point of failure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a single NAT instance in one public subnet
Why it's wrong here
Single point of failure.
- ✓
Use a NAT gateway in each public subnet (one per AZ)
Why this is correct
Highly available and managed.
- ✗
Use a NAT instance in each public subnet (one per AZ)
Why it's wrong here
Highly available but not managed, higher operational overhead.
- ✗
Use a single NAT gateway in one public subnet
Why it's wrong here
Single point of 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.