- A
Elasticity
Why wrong: Incorrect. Elasticity refers to automatically provisioning and releasing resources in response to demand changes. This scenario does not involve dynamic scaling based on fluctuating demand; the same number of instances are used each night.
- B
High availability
Why wrong: 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.
- C
Horizontal scaling
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).
- D
Global reach
Why wrong: 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.
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 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?
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
Option C is correct because 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.
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
Incorrect. Elasticity refers to automatically provisioning and releasing resources in response to demand changes. This scenario does not involve dynamic scaling based on fluctuating demand; the same number of instances are used each night.
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).
Related concept
Read the scenario before looking for a memorised answer.
- ✗
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that 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.
Trap categories for this question
Scenario analysis trap
Incorrect. Elasticity refers to automatically provisioning and releasing resources in response to demand changes. This scenario does not involve dynamic scaling based on fluctuating demand; the same number of instances are used each night.
Detailed technical explanation
How to think about this question
Horizontal scaling in AWS is achieved by adding more EC2 instances behind a load balancer (e.g., Application Load Balancer) or by using a distributed processing framework like AWS Batch or Amazon EMR. Under the hood, each instance processes a distinct data partition (e.g., an S3 prefix or a DynamoDB shard), and failure detection relies on health checks (e.g., ELB health checks or custom heartbeat mechanisms) to trigger reprocessing. A subtle behavior is that horizontal scaling requires the application to be stateless or to externalize state (e.g., in S3 or DynamoDB) so that any instance can pick up a failed chunk without data loss.
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: Horizontal scaling — Option C is correct because 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.
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.
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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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