Question 679 of 988
What Is High Availability in Cloud Computing?
A company is deploying a web application on AWS. The application will run on multiple Amazon EC2 instances distributed across two Availability Zones. An Application Load Balancer will distribute incoming traffic across the instances. The company's primary goal is to ensure the application remains available to users even if one Availability Zone experiences a service disruption. Which cloud computing concept does this architecture primarily demonstrate?
Quick Answer
The answer is high availability. This architecture demonstrates high availability because it eliminates a single point of failure by deploying redundant Amazon EC2 instances across two Availability Zones, with an Application Load Balancer automatically routing traffic away from a failed zone to healthy instances, ensuring continuous uptime. On the AWS Certified Cloud Practitioner CLF-C02 exam, this scenario tests your understanding of the high availability cloud computing concept, often contrasted with fault tolerance or disaster recovery—a common trap is confusing high availability with scalability, but remember that high availability focuses on minimizing downtime through redundancy, not on handling increased load. A useful memory tip: think of high availability as “always on” through duplication across zones, while scalability is “always enough” through adding resources.
⚠ Common exam trap
Many exam-takers confuse high availability with elasticity or scalability, but the key differentiator is that high availability focuses on redundancy and fault tolerance to prevent downtime, not on dynamic resource adjustment or handling increased load.
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
✓
High availability
This architecture demonstrates high availability because it uses multiple EC2 instances across two Availability Zones with an Application Load Balancer to distribute traffic. If one AZ fails, the load balancer automatically routes traffic to the healthy instances in the other AZ, ensuring the application remains accessible. High availability focuses on minimizing downtime by eliminating single points of failure through redundancy.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Elasticity
Why it's wrong here
Elasticity is the ability to automatically add or remove compute resources in response to changing demand. The scenario does not mention scaling based on load; it focuses on maintaining availability during an Availability Zone failure. Therefore, this option is incorrect.
When this WOULD be correct
A question describing an application that automatically adds EC2 instances during peak traffic hours and removes them when demand decreases, using Auto Scaling groups, would make elasticity the correct answer.
- ✗
Scalability
Why it's wrong here
Scalability is the capacity to handle increased workloads by adding resources. While the architecture might be scalable, the primary goal described is availability during a zone failure, not handling increased traffic. Thus, this option is incorrect.
When this WOULD be correct
A question describing an architecture that automatically adds EC2 instances during traffic spikes to maintain performance, such as using Auto Scaling groups with dynamic scaling policies based on CPU utilization.
- ✓
High availability
Why this is correct
High availability ensures that applications remain operational with minimal downtime by using redundant components across multiple Availability Zones and a load balancer. This directly matches the company's goal of remaining available even if one zone fails. This option is correct.
- ✗
Fault tolerance
Why it's wrong here
Fault tolerance is a higher standard than high availability; it aims to keep the system running with zero interruption even when a component fails. The described architecture (standard load balancer and EC2 instances across Availability Zones) is typically associated with high availability, not fault tolerance. Fault-tolerant designs often require more sophisticated failover mechanisms and are less common in standard web applications. Therefore, this option is incorrect.
When this WOULD be correct
A question describing a system that must continue operating without any interruption despite a failure, such as a critical financial transaction system using active-active redundant components across multiple AZs with automatic failover, would make fault tolerance the correct answer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CLF-C02 exam frequently reuses these exact scenarios with slightly different constraints.
✓High availabilityCorrect answer▾
Why this is correct
High availability ensures that applications remain operational with minimal downtime by using redundant components across multiple Availability Zones and a load balancer. This directly matches the company's goal of remaining available even if one zone fails. This option is correct.
✗ElasticityWrong answer — click to see why▾
Why this is wrong here
Elasticity refers to the ability to automatically scale resources up or down based on demand, not to maintaining availability across Availability Zone failures. The architecture's focus on distributing instances across zones to withstand a zone outage is about high availability, not elasticity.
★ When this WOULD be the correct answer
A question describing an application that automatically adds EC2 instances during peak traffic hours and removes them when demand decreases, using Auto Scaling groups, would make elasticity the correct answer.
Why candidates choose this
Candidates may confuse elasticity with high availability because both involve multiple instances and scaling, but elasticity is about dynamic resource adjustment, not fault isolation across zones.
✗ScalabilityWrong answer — click to see why▾
Why this is wrong here
Scalability refers to the ability to handle increased load by adding resources, not to maintaining availability during an AZ failure. The architecture's primary goal is availability despite disruption, not scaling.
★ When this WOULD be the correct answer
A question describing an architecture that automatically adds EC2 instances during traffic spikes to maintain performance, such as using Auto Scaling groups with dynamic scaling policies based on CPU utilization.
Why candidates choose this
Candidates may confuse the ability to add instances across AZs (which supports high availability) with scalability, or think that distributing across AZs inherently scales the application.
✗Fault toleranceWrong answer — click to see why▾
Why this is wrong here
Fault tolerance implies the system can continue operating without interruption even if a component fails, often through redundant components that take over instantly. In this scenario, the architecture uses multiple AZs and an ALB to maintain availability, but it does not guarantee zero downtime or data loss, which fault tolerance requires.
★ When this WOULD be the correct answer
A question describing a system that must continue operating without any interruption despite a failure, such as a critical financial transaction system using active-active redundant components across multiple AZs with automatic failover, would make fault tolerance the correct answer.
Why candidates choose this
Candidates may confuse high availability with fault tolerance because both involve redundancy and failover. They might think that distributing across AZs ensures fault tolerance, but high availability focuses on minimizing downtime, not eliminating it entirely.
Analysis generated from the official CLF-C02blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Same concept, more angles
2 more ways this is tested on CLF-C02
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 runs a web application on a single Amazon EC2 instance. To improve the application's ability to remain operational even if an entire data center becomes unavailable, the company deploys identical application instances across three AWS Availability Zones and places them behind an Application Load Balancer. Which characteristic of cloud computing does this architecture best demonstrate?
medium- A.Elasticity
- ✓ B.High availability
- C.Scalability
- D.Agility
Why B: Deploying identical application instances across three Availability Zones and placing them behind an Application Load Balancer ensures that if an entire data center (AZ) becomes unavailable, traffic is automatically rerouted to healthy instances in the remaining AZs. This architecture directly demonstrates high availability, which is the ability of a system to remain operational despite component failures, by eliminating a single point of failure at the data center level.
Variation 2. A company runs a critical e-commerce application on Amazon EC2 instances distributed across multiple Availability Zones in a single AWS Region. The application is designed so that if an entire Availability Zone experiences an outage, the application continues to serve traffic from the remaining Availability Zones without interruption. Which benefit or characteristic of cloud computing does this scenario BEST represent?
medium- A.Elasticity
- B.High availability
- C.Scalability
- ✓ D.Fault tolerance
Why D: The scenario describes an application that continues to operate without interruption when an entire Availability Zone fails. This is the definition of fault tolerance, which refers to a system's ability to remain fully operational with no downtime even when components fail. While high availability also uses redundancy across multiple Availability Zones, it typically allows for minimal downtime during failover. Fault tolerance goes further by eliminating any interruption, making it the best fit for the 'without interruption' condition described.
Last reviewed: Jun 11, 2026
This CLF-C02 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 CLF-C02 exam.
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