CLF-C02 Cloud Concepts Practice Question
A company runs a customer-facing web application with an Amazon RDS database. Initially, the database is deployed as a single instance in one Availability Zone (AZ). A power outage occurs in that AZ, causing the database to become unavailable for several hours. After the incident, the company modifies the database to use a Multi-AZ configuration. Shortly after the change, another power outage affects the same primary AZ. This time, the database automatically fails over to the standby instance in the other AZ without any manual intervention, and the application remains available. Which cloud computing concept does this scenario best demonstrate?
⚠ Common exam trap
Test-takers frequently confuse fault tolerance with high availability or elasticity, but fault tolerance specifically implies zero downtime during a failure, whereas high availability may involve a brief interruption, and elasticity is about scaling, not failure recovery.
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 ability of a system to continue operating without interruption when one or more of its components fail. In this scenario, the Multi-AZ RDS deployment automatically failed over to a standby instance in a different Availability Zone when the primary AZ experienced a power outage, ensuring the application remained available without manual intervention. This demonstrates fault tolerance because the system was designed to withstand the failure of an entire AZ and continue functioning.
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 refers to the ability to automatically provision and de-provision resources to match demand. The scenario does not involve scaling up or down based on load; it is about surviving a failure. Therefore, elasticity is not the correct concept.
When this WOULD be correct
A company's web application experiences fluctuating traffic; during peak hours, the application automatically adds more EC2 instances to handle the load, and removes them during off-peak hours. This demonstrates elasticity.
- ✓
Fault tolerance
Why this is correct
Fault tolerance is the correct concept. The Multi-AZ RDS configuration allows the database to automatically fail over to a standby instance in a different Availability Zone when the primary fails. This ensures continuous operation despite a component failure, which is the definition of fault tolerance.
- ✗
Scalability
Why it's wrong here
Scalability is the ability to increase or decrease resources to handle varying workloads. While Auto Scaling would demonstrate scalability, this scenario does not involve changing the amount of resources; it is about ensuring availability during a failure. Thus, scalability is not the best answer.
When this WOULD be correct
A web application experiences sudden traffic spikes during a flash sale. The company uses Auto Scaling to automatically add EC2 instances and RDS read replicas to handle the increased load, then removes them when traffic subsides. This demonstrates scalability.
- ✗
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 using a multi-tenant model. The scenario is about database redundancy across AZs, not about sharing resources among customers. Therefore, resource pooling is incorrect.
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
Fault tolerance is the correct concept. The Multi-AZ RDS configuration allows the database to automatically fail over to a standby instance in a different Availability Zone when the primary fails. This ensures continuous operation despite a component failure, which is the definition of fault tolerance.
✗ElasticityWrong answer — click to see why▾
Why this is wrong here
Elasticity refers to automatically scaling resources up or down based on demand, not to maintaining availability during failures. The scenario describes automatic failover to a standby instance, which is fault tolerance, not elasticity.
★ When this WOULD be the correct answer
A company's web application experiences fluctuating traffic; during peak hours, the application automatically adds more EC2 instances to handle the load, and removes them during off-peak hours. This demonstrates elasticity.
Why candidates choose this
Candidates may confuse the automatic failover with automatic scaling, thinking that the system 'adapts' to the failure, but elasticity specifically deals with scaling based on load, not failure recovery.
✗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 availability during failures. The scenario describes automatic failover to a standby instance, which is fault tolerance, not scaling.
★ When this WOULD be the correct answer
A web application experiences sudden traffic spikes during a flash sale. The company uses Auto Scaling to automatically add EC2 instances and RDS read replicas to handle the increased load, then removes them when traffic subsides. This demonstrates scalability.
Why candidates choose this
Candidates may confuse the ability to handle increased load (scalability) with the ability to withstand failures (fault tolerance), especially since both involve redundancy and automatic responses.
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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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.