CLF-C02 Cloud Concepts Practice Question
A retail company runs a web application on Amazon EC2 instances behind an Application Load Balancer. During a promotional event, traffic spikes to 10 times the normal level. The company configured an Amazon EC2 Auto Scaling group with a scaling policy that adds instances when CPU utilization exceeds 70% and removes instances when it drops below 30%. The application handles the spike without any manual intervention, and after the event ends, the number of instances automatically decreases to the original count, saving costs. This scenario best demonstrates which cloud computing concept?
⚠ Common exam trap
Many exam-takers confuse scalability with elasticity, but scalability only implies the ability to grow (scale up/out), while elasticity explicitly includes the ability to shrink (scale down/in) to match demand and optimize costs.
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
✓
Elasticity
The scenario describes the system automatically scaling out to 10 times the normal capacity during a traffic spike and then scaling back down when the spike ends, which is the definition of elasticity—the ability to dynamically provision and de-provision resources to match demand. The use of an EC2 Auto Scaling group with a CPU-based scaling policy (70% threshold to add, 30% to remove) directly demonstrates this cloud computing concept, as it handles variable workloads without manual intervention and optimizes cost by reducing resources when they are no longer needed.
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 this is correct
Elasticity in AWS is the ability to automatically and dynamically add or remove compute capacity in response to real-time changes in demand. An Auto Scaling group with a scaling policy uses CloudWatch monitoring metrics to add EC2 instances when traffic spikes and terminate instances when traffic subsides, matching capacity exactly to the current workload. This bidirectional, automated adjustment is the characteristic that makes the scenario a textbook example of elasticity.
- ✗
Scalability
Why it's wrong here
Scalability is the ability to handle increased load by adding resources, but it does not inherently imply automatic scaling down. While the system is scalable, the key feature demonstrated is the dynamic, bidirectional adjustment that defines elasticity.
When this WOULD be correct
A scenario where a company plans for future growth by designing a system that can handle increased load over time, such as migrating from a single EC2 instance to a multi-tier architecture with Auto Scaling to support a growing user base, would best demonstrate scalability.
- ✗
High availability
Why it's wrong here
High availability ensures the application remains accessible despite component failures, often through redundancy across multiple Availability Zones. The scenario does not describe a failure or redundancy configuration; it focuses on scaling to meet variable demand.
When this WOULD be correct
A question describing an application deployed across multiple Availability Zones with automatic failover to maintain uptime during an AZ outage would make high availability the correct answer. For example: 'A company runs a web application on EC2 instances in two Availability Zones. If one AZ fails, traffic is automatically redirected to the other AZ. This demonstrates which concept?'
- ✗
Fault tolerance
Why it's wrong here
Fault tolerance is the property that lets an application continue operating without interruption even when a component, such as an EC2 instance or Availability Zone, fails. The scenario describes only a variation in customer traffic and the corresponding scaling actions; there is no mention of a failed instance, a failed dependency, or a redundant architecture designed to mask component loss. Auto Scaling can replace unhealthy instances, but here the group is responding to load changes, not to a fault event, so fault tolerance is not the concept being tested.
When this WOULD be correct
A question describing an application that continues to serve requests without downtime after an EC2 instance fails, due to redundant instances in multiple Availability Zones, would have fault tolerance as 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.
✓ElasticityCorrect answer▾
Why this is correct
Elasticity in AWS is the ability to automatically and dynamically add or remove compute capacity in response to real-time changes in demand. An Auto Scaling group with a scaling policy uses CloudWatch monitoring metrics to add EC2 instances when traffic spikes and terminate instances when traffic subsides, matching capacity exactly to the current workload. This bidirectional, automated adjustment is the characteristic that makes the scenario a textbook example of elasticity.
✗ScalabilityWrong answer — click to see why▾
Why this is wrong here
Scalability refers to the ability to handle increased load by adding resources, but it does not inherently include the ability to automatically reduce resources when demand decreases, which is the key aspect demonstrated by the scenario (cost savings after the event).
★ When this WOULD be the correct answer
A scenario where a company plans for future growth by designing a system that can handle increased load over time, such as migrating from a single EC2 instance to a multi-tier architecture with Auto Scaling to support a growing user base, would best demonstrate scalability.
Why candidates choose this
Candidates often confuse elasticity with scalability because both involve adding resources; however, elasticity specifically includes the automatic scaling down to save costs, which is the distinguishing feature in this question.
✗High availabilityWrong answer — click to see why▾
Why this is wrong here
High availability focuses on ensuring the application remains accessible despite failures (e.g., across multiple Availability Zones), not on automatically adjusting resources to match fluctuating demand. The scenario describes scaling resources up and down based on load, which is elasticity.
★ When this WOULD be the correct answer
A question describing an application deployed across multiple Availability Zones with automatic failover to maintain uptime during an AZ outage would make high availability the correct answer. For example: 'A company runs a web application on EC2 instances in two Availability Zones. If one AZ fails, traffic is automatically redirected to the other AZ. This demonstrates which concept?'
Why candidates choose this
Candidates may confuse high availability with elasticity because both involve redundancy and automatic responses, but high availability is about uptime and fault tolerance, not dynamic scaling of resources based on demand.
✗Fault toleranceWrong answer — click to see why▾
Why this is wrong here
Fault tolerance refers to a system's ability to continue operating without interruption despite component failures. The scenario describes automatic scaling to handle traffic spikes, not recovery from failures.
★ When this WOULD be the correct answer
A question describing an application that continues to serve requests without downtime after an EC2 instance fails, due to redundant instances in multiple Availability Zones, would have fault tolerance as the correct answer.
Why candidates choose this
Candidates may confuse the automatic scaling and self-healing aspects of Auto Scaling with fault tolerance, not realizing that fault tolerance specifically addresses failure recovery, not demand-based scaling.
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?”
Go deeper
Related to this question
About these practice questions
Courseiva writes every CLF-C02 question from scratch — 988 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
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.