CLF-C02 Cloud Concepts Practice Question
A company runs a nightly batch processing job on a single on-premises server. The job takes 4 hours to complete, and if the server fails during processing, the job must start over from the beginning. The company is migrating this workload to AWS. The solutions architect proposes running the job across multiple Amazon EC2 instances that process different chunks of data simultaneously. The architect also plans to configure the system so that if any single instance fails, its chunk is automatically reprocessed by another instance, ensuring the overall job still completes. Which benefit of cloud computing does this architecture primarily demonstrate?
⚠ Common exam trap
A common mix-up: candidates confuse fault tolerance (handling instance failure) with high availability, but the question emphasizes distributing work across multiple instances to complete the job faster and handle failures, which is the core benefit of horizontal scaling, not just keeping the system running.
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
✓
Horizontal scaling
The architecture distributes the workload across multiple EC2 instances, each processing a separate chunk of data. This is the definition of horizontal scaling (scaling out). If an instance fails, its chunk is automatically reprocessed by another instance, which demonstrates the fault tolerance and parallelism that horizontal scaling enables, not just adding more capacity.
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 describes a system's ability to automatically add or remove compute capacity in real time to match fluctuating demand, typically using AWS Auto Scaling or managed services like Lambda. In this scenario, the architect manually splits the job across a fixed set of EC2 instances each night; there is no dynamic, demand-driven provisioning or deprovisioning of resources. Because the workload size and instance count remain constant, the design does not exhibit elasticity.
When this WOULD be correct
A company runs a web application that experiences unpredictable traffic spikes. The solutions architect proposes using Auto Scaling groups to automatically add EC2 instances during high demand and remove them when demand drops. This architecture primarily demonstrates elasticity.
- ✗
High availability
Why it's wrong here
Incorrect. High availability focuses on minimizing downtime and ensuring the system is operational. While the design provides some availability benefit (job continues despite failure), the primary goal is to improve performance through parallel processing, which is horizontal scaling.
When this WOULD be correct
A company runs a critical web application on a single EC2 instance. To ensure the application remains accessible even if that instance fails, the solutions architect deploys the application across multiple EC2 instances in different Availability Zones with an Auto Scaling group and a load balancer. This architecture primarily demonstrates high availability.
- ✓
Horizontal scaling
Why this is correct
Correct. Horizontal scaling (scaling out) means adding more instances to share the workload. The architect splits the job into chunks and runs them on multiple EC2 instances, improving both performance (parallelism) and fault tolerance (chunks are reprocessed if an instance fails).
- ✗
Global reach
Why it's wrong here
Incorrect. Global reach refers to deploying resources in multiple geographic regions to reduce latency or meet data residency requirements. This scenario does not mention multiple regions; all instances are assumed to be in the same region.
When this WOULD be correct
A company wants to serve users worldwide with low latency. The solutions architect proposes deploying the application in multiple AWS regions and using Amazon CloudFront for content delivery. This architecture primarily demonstrates global reach.
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.
✓Horizontal scalingCorrect answer▾
Why this is correct
Correct. Horizontal scaling (scaling out) means adding more instances to share the workload. The architect splits the job into chunks and runs them on multiple EC2 instances, improving both performance (parallelism) and fault tolerance (chunks are reprocessed if an instance fails).
✗ElasticityWrong answer — click to see why▾
Why this is wrong here
Elasticity refers to automatically scaling resources up or down based on demand, but the architecture described focuses on splitting work across multiple instances and handling failures, not on dynamic scaling.
★ When this WOULD be the correct answer
A company runs a web application that experiences unpredictable traffic spikes. The solutions architect proposes using Auto Scaling groups to automatically add EC2 instances during high demand and remove them when demand drops. This architecture primarily demonstrates elasticity.
Why candidates choose this
Candidates may confuse the ability to add more instances (which is a form of scaling) with elasticity, but elasticity specifically involves dynamic adjustment to workload changes, not just distributing work across fixed instances.
✗High availabilityWrong answer — click to see why▾
Why this is wrong here
High availability focuses on ensuring the system remains operational and accessible despite failures, typically through redundancy and failover. In this scenario, the job still completes even if an instance fails, but the primary benefit demonstrated is the ability to add more instances to process data in parallel (horizontal scaling), not the overall uptime of the system.
★ When this WOULD be the correct answer
A company runs a critical web application on a single EC2 instance. To ensure the application remains accessible even if that instance fails, the solutions architect deploys the application across multiple EC2 instances in different Availability Zones with an Auto Scaling group and a load balancer. This architecture primarily demonstrates high availability.
Why candidates choose this
Candidates may confuse the automatic reprocessing of failed chunks with high availability, as both involve handling failures. However, high availability is about maintaining service uptime, not about distributing workload across instances for parallel processing.
✗Global reachWrong answer — click to see why▾
Why this is wrong here
Global reach refers to deploying applications in multiple geographic regions to reduce latency and comply with data residency requirements, which is not relevant to the scenario of distributing a batch job across multiple instances for fault tolerance.
★ When this WOULD be the correct answer
A company wants to serve users worldwide with low latency. The solutions architect proposes deploying the application in multiple AWS regions and using Amazon CloudFront for content delivery. This architecture primarily demonstrates global reach.
Why candidates choose this
Candidates may confuse the ability to use multiple instances with the concept of global distribution, or they might think that running across multiple instances implies geographic dispersion.
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. Which statement correctly describes the difference between horizontal scaling and vertical scaling in cloud computing?
medium- A.Horizontal scaling means increasing instance size; vertical scaling means adding more instances
- ✓ B.Horizontal scaling adds more instances; vertical scaling increases the size of existing instances
- C.Both scaling types produce identical results and are interchangeable in cloud architectures
- D.Vertical scaling is always preferred because it reduces the number of instances to manage
Why B: Horizontal scaling (scaling out) involves adding more instances of a resource, such as EC2 instances, to distribute the load, while vertical scaling (scaling up) increases the size or capacity of an existing instance, for example by moving from a t2.micro to a t2.large. This distinction is fundamental in AWS cloud architectures, where horizontal scaling improves fault tolerance and availability, and vertical scaling is limited by the maximum instance size.
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.