Question 768 of 988
CLF-C02 Cloud Concepts Practice Question
A startup is deploying a web application on Amazon EC2 instances across multiple Availability Zones (AZs). The architecture must ensure that the application remains fully operational and available to users even if one entire AZ fails. Which cloud computing concept does this requirement MOST directly represent?
⚠ Common exam trap
Many exam-takers confuse fault tolerance with high availability, but fault tolerance specifically implies zero downtime and no data loss during a failure, whereas high availability may allow for brief interruptions or degraded performance.
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
✓
Fault tolerance
Fault tolerance is the correct concept because the requirement specifies that the application must remain fully operational and available even if an entire Availability Zone fails. By deploying EC2 instances across multiple AZs and using an Elastic Load Balancer to distribute traffic, the architecture can withstand the failure of one AZ without any interruption in service, which is the essence of fault tolerance.
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 of a cloud system to automatically scale computing capacity up or down in response to changing demand, typically implemented with services like Amazon EC2 Auto Scaling. It matches the number of running resources to the current workload, so you pay for exactly what you need and can handle traffic spikes by adding instances. However, elasticity alone does not guarantee that those instances are distributed across multiple Availability Zones, nor does it provide any mechanism to maintain service if an entire zone fails. A single-AZ deployment with elastic scaling still has a single point of failure, so elasticity is concerned with capacity alignment, not continuous availability during a data center outage.
When this WOULD be correct
A question that asks: 'A web application experiences variable traffic spikes. Which cloud computing concept allows the system to automatically add or remove EC2 instances to match the current load?' would make elasticity the correct answer.
- ✓
Fault tolerance
Why this is correct
Correct. Fault tolerance describes a system that continues operating without interruption despite the failure of one or more components. Distributing workloads across multiple Availability Zones is a key method to achieve fault tolerance in AWS.
- ✗
Scalability
Why it's wrong here
Scalability is the ability of a system to support increasing workloads by adding resources, either through vertical scaling (larger instances) or horizontal scaling (more instances). It focuses on performance and throughput under load, ensuring the application can grow without degrading responsiveness. But scalability does not inherently include redundancy or failover; a scalable system could run on one large instance or a set of instances all placed in the same Availability Zone, and it would still go down if that zone fails. Thus scalability is about managing growth, not about surviving component failure, making it incorrect for this question because it lacks the fault-tolerant characteristics needed for uninterrupted operation.
When this WOULD be correct
A question asking: 'A company expects a sudden spike in traffic for a new product launch. Which cloud concept ensures the application can automatically add EC2 instances to handle the increased load?' would make scalability correct.
- ✗
Resource pooling
Why it's wrong here
Resource pooling is a foundational characteristic of cloud computing where the provider's physical and virtual resources are dynamically assigned and reassigned among multiple customers, enabling multi-tenancy and cost efficiency. It is about how the cloud shares infrastructure, not about how an individual workload survives component failures. Even if resources are pooled across many customers, a single Availability Zone outage can still take down every instance running in that zone, because pooling provides no mechanism for detecting a failure or redirecting traffic. Therefore, resource pooling is incorrect because it addresses the provider's operational model, not the application's resilience to an Availability Zone failure.
When this WOULD be correct
A question asking which cloud characteristic allows multiple customers to use the same physical infrastructure securely and independently would make resource pooling 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.
✓Fault toleranceCorrect answer▾
Why this is correct
Correct. Fault tolerance describes a system that continues operating without interruption despite the failure of one or more components. Distributing workloads across multiple Availability Zones is a key method to achieve fault tolerance in AWS.
✗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 maintain operation during an AZ failure. The question specifically asks about surviving an AZ failure, which is fault tolerance.
★ When this WOULD be the correct answer
A question that asks: 'A web application experiences variable traffic spikes. Which cloud computing concept allows the system to automatically add or remove EC2 instances to match the current load?' would make elasticity the correct answer.
Why candidates choose this
Candidates may confuse elasticity with high availability or fault tolerance because both involve handling changes in the environment, but elasticity is about scaling, not surviving failures.
✗ScalabilityWrong answer — click to see why▾
Why this is wrong here
Scalability refers to the ability to increase or decrease resources to handle varying load, not to maintain operation during an AZ failure. The requirement is about surviving a failure, not adjusting to demand.
★ When this WOULD be the correct answer
A question asking: 'A company expects a sudden spike in traffic for a new product launch. Which cloud concept ensures the application can automatically add EC2 instances to handle the increased load?' would make scalability correct.
Why candidates choose this
Candidates may confuse fault tolerance with scalability because both involve multiple instances, but scalability focuses on performance under load, not failure resilience.
✗Resource poolingWrong answer — click to see why▾
Why this is wrong here
Resource pooling refers to the provider's ability to serve multiple customers from shared physical resources, not to application availability across AZ failures.
★ When this WOULD be the correct answer
A question asking which cloud characteristic allows multiple customers to use the same physical infrastructure securely and independently would make resource pooling the correct answer.
Why candidates choose this
Candidates may confuse resource pooling with high availability or fault tolerance because both involve distributing workloads across multiple resources.
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
1 more way 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 deploys their web application across two Availability Zones using an Application Load Balancer. If one AZ experiences an outage, traffic is automatically routed to the other AZ and the application continues to function. Which cloud benefit does this demonstrate?
medium- A.Economies of scale
- B.On-demand self-service
- ✓ C.High availability and fault tolerance
- D.Rapid elasticity
Why C: This scenario demonstrates high availability and fault tolerance because the application is deployed across two Availability Zones with an Application Load Balancer (ALB) distributing traffic. If one AZ fails, the ALB automatically reroutes traffic to the healthy AZ, ensuring continuous operation. This design eliminates a single point of failure and maintains service availability, which is the core of fault tolerance in AWS.
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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