This ANS-C01 practice question tests your understanding of network design. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 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?
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.
Option C is correct because 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.
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 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.
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.
Related concept
Read the scenario before looking for a memorised answer.
✗
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often 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.
Detailed technical explanation
How to think about this question
An Application Load Balancer operates at Layer 7 and uses target groups to route traffic to instances based on health checks and listener rules. When cross-zone load balancing is enabled (default for ALB), the ALB distributes incoming traffic evenly across all registered instances in all AZs, regardless of which AZ the load balancer nodes reside in. In a real-world scenario, if an ALB has nodes in two AZs and instances in two AZs, the loss of one AZ causes the ALB to fail over to the remaining node, which continues to serve traffic to healthy instances in the surviving AZ, maintaining availability.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Deploy application instances in two AZs behind an Application Load Balancer that spans both AZs. — Option C is correct because 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.
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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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.
Question Discussion
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