- A
Elasticity
Why wrong: Elasticity is the ability to automatically scale computing resources up or down based on demand. This concept is about matching capacity to workload, not about surviving an Availability Zone failure.
- B
Fault tolerance
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.
- C
Scalability
Why wrong: Scalability is the ability to handle increasing loads by adding resources. While related to growth, it does not inherently ensure continuous operation when a whole data center fails.
- D
Resource pooling
Why wrong: Resource pooling is a characteristic of cloud computing where the provider's computing resources are pooled to serve multiple customers (multi-tenancy). It does not directly address failure recovery across data centers.
Quick Answer
The answer is fault tolerance. This is correct because fault tolerance is the cloud computing concept that guarantees a system remains fully operational with zero interruption, even when an entire Availability Zone fails, as achieved by deploying EC2 instances across multiple AZs behind an Elastic Load Balancer. On the AWS Certified Cloud Practitioner CLF-C02 exam, this distinction tests your ability to separate fault tolerance from high availability: high availability aims for minimal downtime (e.g., 99.99% uptime), while fault tolerance demands continuous operation without any break in service. A common trap is confusing the two when a question specifies “fully operational” or “no interruption” during a failure—those are clear signals for fault tolerance. Remember the memory tip: “Fault tolerance = no fault tolerated, zero downtime; high availability = almost always up, but a brief blip is acceptable.”
CLF-C02 Cloud Concepts Practice Question
This CLF-C02 practice question tests your understanding of cloud concepts. 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 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?
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.
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.
- ✗
Elasticity
Why it's wrong here
Elasticity is the ability to automatically scale computing resources up or down based on demand. This concept is about matching capacity to workload, not about surviving an Availability Zone failure.
- ✓
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.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Scalability
Why it's wrong here
Scalability is the ability to handle increasing loads by adding resources. While related to growth, it does not inherently ensure continuous operation when a whole data center fails.
- ✗
Resource pooling
Why it's wrong here
Resource pooling is a characteristic of cloud computing where the provider's computing resources are pooled to serve multiple customers (multi-tenancy). It does not directly address failure recovery across data centers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often 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.
Detailed technical explanation
How to think about this question
Fault tolerance in AWS is achieved through redundancy and automated failover mechanisms. For example, deploying EC2 instances in at least two AZs behind an Application Load Balancer (ALB) with health checks ensures that traffic is only routed to healthy instances. If an entire AZ fails, the ALB automatically stops sending requests to that AZ's instances, and the application continues to serve users from the remaining AZs. This design relies on the AWS global infrastructure's isolated AZs, which are connected via low-latency links but are independent in terms of power, cooling, and physical location.
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.
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Cloud Concepts — This question tests Cloud Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this CLF-C02 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 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 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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