ANS-C01 Network Design Practice Question
A company is designing a VPC with subnets in multiple Availability Zones (AZs) for a web application. The application must be fault-tolerant and highly available. Which design should the network engineer implement?
⚠ Common exam trap
Many exam-takers assume a single load balancer in one AZ is sufficient if instances are in multiple AZs, but they overlook that the load balancer itself must be deployed across multiple AZs to avoid being a single point of failure.
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 application instances in two AZs behind an Application Load Balancer that spans both AZs.
Deploying application instances in two Availability Zones (AZs) behind an Application Load Balancer (ALB) that spans both AZs provides fault tolerance and high availability. If one AZ fails, the ALB automatically routes traffic to healthy instances in the remaining AZ, ensuring continuous service. This design leverages cross-zone load balancing, which is enabled by default for ALBs, to distribute traffic evenly across instances in multiple AZs.
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 all application instances in a single AZ behind an Application Load Balancer.
Why it's wrong here
A single AZ can go down, causing application failure.
- ✗
Place one instance in each of two AZs and use an internet gateway for load balancing.
Why it's wrong here
An internet gateway does not perform load balancing; it's a routing target.
- ✓
Deploy application instances in two AZs behind an Application Load Balancer that spans both AZs.
Why this is correct
This provides fault tolerance and high availability across AZs.
- ✗
Use a Network Load Balancer in a single AZ with instances in multiple AZs.
Why it's wrong here
Network Load Balancer can target instances in multiple AZs, but the question implies fault tolerance requires multiple AZs for instances.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 1,621 original ANS-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company wants to improve the performance and availability of its application that is deployed on EC2 instances in a single Availability Zone. Which architecture should the company implement?
easy- A.Add more subnets in the same Availability Zone
- ✓ B.Deploy EC2 instances in multiple Availability Zones
- C.Use larger EC2 instances
- D.Use Auto Scaling in the same Availability Zone
Why B: Deploying EC2 instances across multiple Availability Zones (AZs) improves both performance and availability by eliminating a single point of failure. If one AZ experiences an outage, traffic can be routed to healthy instances in another AZ using an Elastic Load Balancer or Route 53 DNS failover. This architecture also distributes the load, reducing latency for users in different geographic regions.
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.