- A
AWS Lambda
Why wrong: Standard AWS Lambda functions run in regional AWS endpoints, not at edge locations. While they are serverless, they do not provide the edge-based processing required to generate thumbnails close to global users.
- B
AWS Lambda@Edge
AWS Lambda@Edge is a feature of Amazon CloudFront that runs Lambda functions at AWS edge locations in response to CloudFront events. It is serverless, scales automatically, and is ideal for processing content close to users, such as on-the-fly thumbnail generation.
- C
Amazon EC2 instances in an Auto Scaling group
Why wrong: EC2 instances require provisioning, patching, and capacity management. They run in specific AWS Regions, not at edge locations, and are not a serverless solution. This would not reduce latency as effectively as edge computing.
- D
Amazon ElastiCache
Why wrong: Amazon ElastiCache is a caching service that improves application performance by retrieving data from fast, managed in-memory caches. It is not designed to run custom code or generate thumbnails.
CLF-C02 Cloud Technology and Services Practice Question
This CLF-C02 practice question tests your understanding of cloud technology and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 media company runs a website that serves video content globally. Users request video previews, which require the generation of thumbnail images on-the-fly. The company wants to generate these thumbnails at AWS edge locations so that the processing occurs close to users, reducing latency and offloading the origin servers. The solution must run custom code in response to CloudFront events without provisioning any servers. Which AWS service should the company use to meet these requirements?
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
AWS Lambda@Edge
AWS Lambda@Edge is the correct service because it allows you to run custom code in response to CloudFront events (such as viewer request, origin request, viewer response, and origin response) at AWS edge locations, enabling on-the-fly thumbnail generation close to users without provisioning any servers. This reduces latency and offloads origin servers, meeting the requirement for serverless edge processing.
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.
- ✗
AWS Lambda
Why it's wrong here
Standard AWS Lambda functions run in regional AWS endpoints, not at edge locations. While they are serverless, they do not provide the edge-based processing required to generate thumbnails close to global users.
When this WOULD be correct
A company needs to process uploaded images in a central S3 bucket, generating thumbnails asynchronously. The solution must run custom code without servers, triggered by S3 events. AWS Lambda would be correct because it can be triggered by S3 events and does not require edge processing.
- ✓
AWS Lambda@Edge
Why this is correct
AWS Lambda@Edge is a feature of Amazon CloudFront that runs Lambda functions at AWS edge locations in response to CloudFront events. It is serverless, scales automatically, and is ideal for processing content close to users, such as on-the-fly thumbnail generation.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Amazon EC2 instances in an Auto Scaling group
Why it's wrong here
EC2 instances require provisioning, patching, and capacity management. They run in specific AWS Regions, not at edge locations, and are not a serverless solution. This would not reduce latency as effectively as edge computing.
When this WOULD be correct
A company needs to run a custom video transcoding application that requires significant CPU and memory resources, and the processing must be scalable and fault-tolerant. The solution can provision EC2 instances in an Auto Scaling group behind an Application Load Balancer to handle the workload, and server management is acceptable.
- ✗
Amazon ElastiCache
Why it's wrong here
Amazon ElastiCache is a caching service that improves application performance by retrieving data from fast, managed in-memory caches. It is not designed to run custom code or generate thumbnails.
When this WOULD be correct
A company wants to reduce latency for frequently accessed database query results by caching them at edge locations. The solution must use a managed caching service that integrates with CloudFront without provisioning servers.
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.
✓AWS Lambda@EdgeCorrect answer▾
Why this is correct
AWS Lambda@Edge is a feature of Amazon CloudFront that runs Lambda functions at AWS edge locations in response to CloudFront events. It is serverless, scales automatically, and is ideal for processing content close to users, such as on-the-fly thumbnail generation.
✗AWS LambdaWrong answer — click to see why▾
Why this is wrong here
AWS Lambda cannot be triggered directly by CloudFront events at edge locations; it runs only in specific AWS regions, not at edge locations, so it cannot process requests close to users globally.
★ When this WOULD be the correct answer
A company needs to process uploaded images in a central S3 bucket, generating thumbnails asynchronously. The solution must run custom code without servers, triggered by S3 events. AWS Lambda would be correct because it can be triggered by S3 events and does not require edge processing.
Why candidates choose this
Candidates know Lambda is serverless and runs custom code, but they overlook that Lambda@Edge is the variant designed to run at CloudFront edge locations in response to CloudFront events.
✗Amazon EC2 instances in an Auto Scaling groupWrong answer — click to see why▾
Why this is wrong here
Amazon EC2 instances in an Auto Scaling group require provisioning and managing servers, which contradicts the requirement to run custom code without provisioning any servers. Additionally, EC2 instances are not integrated with CloudFront events at edge locations.
★ When this WOULD be the correct answer
A company needs to run a custom video transcoding application that requires significant CPU and memory resources, and the processing must be scalable and fault-tolerant. The solution can provision EC2 instances in an Auto Scaling group behind an Application Load Balancer to handle the workload, and server management is acceptable.
Why candidates choose this
Candidates may think that EC2 instances can be used to run custom code for thumbnail generation, and Auto Scaling can handle variable loads, overlooking the serverless and edge-processing requirements specified in the question.
✗Amazon ElastiCacheWrong answer — click to see why▾
Why this is wrong here
Amazon ElastiCache is a caching service for in-memory data, not for running custom code at edge locations. It cannot generate thumbnail images on-the-fly in response to CloudFront events.
★ When this WOULD be the correct answer
A company wants to reduce latency for frequently accessed database query results by caching them at edge locations. The solution must use a managed caching service that integrates with CloudFront without provisioning servers.
Why candidates choose this
Candidates may confuse caching (ElastiCache) with edge compute (Lambda@Edge), thinking that caching thumbnails at the edge would solve the problem, but the requirement is to generate thumbnails on-the-fly, not cache pre-generated ones.
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 often confuse standard AWS Lambda with Lambda@Edge, assuming Lambda can run at edge locations, but standard Lambda is region-bound and cannot intercept CloudFront events at the edge.
Detailed technical explanation
How to think about this question
Lambda@Edge functions are replicated to CloudFront edge locations worldwide and are triggered by CloudFront events, with a maximum execution timeout of 5 seconds for viewer-request and viewer-response events and 30 seconds for origin-request and origin-response events. The function code must be authored in the US East (N. Virginia) Region, and it can manipulate HTTP requests and responses, including generating binary thumbnails from video previews, but it cannot access VPC resources or use environment variables larger than 10 KB.
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
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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 Technology and Services — This question tests Cloud Technology and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: AWS Lambda@Edge — AWS Lambda@Edge is the correct service because it allows you to run custom code in response to CloudFront events (such as viewer request, origin request, viewer response, and origin response) at AWS edge locations, enabling on-the-fly thumbnail generation close to users without provisioning any servers. This reduces latency and offloads origin servers, meeting the requirement for serverless edge processing.
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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