- A
AWS Lambda
AWS Lambda is correct. It executes code in response to S3 events, scales automatically, and is serverless, meaning no server management is needed.
- B
AWS Batch
Why wrong: AWS Batch is designed for batch computing jobs that run on managed EC2 instances or Fargate. It is not event-driven by default and would require provisioning and managing compute environments, making it less suitable for this simple event-triggered task.
- C
Amazon EC2
Why wrong: Amazon EC2 instances run continuously and require manual scaling and management. Using EC2 for occasional thumbnail creation would lead to idle resource costs and operational overhead, contradicting the requirement for a serverless, event-driven solution.
- D
Amazon ECS with EC2 launch type
Why wrong: Amazon ECS with the EC2 launch type requires managing a cluster of EC2 instances. While it can run containers, it is not serverless and does not automatically trigger based on S3 events without additional components like Lambda or EventBridge.
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 company has a mobile application that allows users to upload profile photos. When a new photo is uploaded to an Amazon S3 bucket, the application must automatically create a thumbnail version and store it in another S3 bucket. The company wants a solution that runs only when needed, scales automatically, and requires no management of underlying 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
AWS Lambda is the correct choice because it is a serverless compute service that runs code in response to events, such as an S3 PUT object event. It automatically scales from zero to thousands of concurrent executions based on the number of incoming uploads, and requires no server management, perfectly meeting the requirement for an on-demand, auto-scaling thumbnail generation solution.
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 this is correct
AWS Lambda is correct. It executes code in response to S3 events, scales automatically, and is serverless, meaning no server management is needed.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
AWS Batch
Why it's wrong here
AWS Batch is designed for batch computing jobs that run on managed EC2 instances or Fargate. It is not event-driven by default and would require provisioning and managing compute environments, making it less suitable for this simple event-triggered task.
- ✗
Amazon EC2
Why it's wrong here
Amazon EC2 instances run continuously and require manual scaling and management. Using EC2 for occasional thumbnail creation would lead to idle resource costs and operational overhead, contradicting the requirement for a serverless, event-driven solution.
- ✗
Amazon ECS with EC2 launch type
Why it's wrong here
Amazon ECS with the EC2 launch type requires managing a cluster of EC2 instances. While it can run containers, it is not serverless and does not automatically trigger based on S3 events without additional components like Lambda or EventBridge.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse AWS Batch with event-driven processing, but Batch is optimized for scheduled or queued batch jobs, not for real-time, per-object triggers like S3 uploads.
Detailed technical explanation
How to think about this question
Under the hood, AWS Lambda integrates with S3 via event notifications: when a new object is created, S3 publishes a notification to Lambda, which then invokes the function with the event payload containing the bucket name and object key. The function can use the AWS SDK to download the original image, generate a thumbnail using a library like Pillow, and upload the result to the destination bucket. A key subtlety is that Lambda has a maximum execution timeout of 15 minutes and a maximum deployment package size of 250 MB (uncompressed), so for very large images or complex processing, you might need to consider AWS Lambda Extensions or step functions.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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 — AWS Lambda is the correct choice because it is a serverless compute service that runs code in response to events, such as an S3 PUT object event. It automatically scales from zero to thousands of concurrent executions based on the number of incoming uploads, and requires no server management, perfectly meeting the requirement for an on-demand, auto-scaling thumbnail generation solution.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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