DVA-C02 S3 Event Notification Practice Question
A developer is designing a serverless application that processes large files uploaded to Amazon S3. Each file can be up to 5 GB. The processing involves extracting metadata and generating thumbnails. The developer wants to minimize processing time and cost. Which approach should the developer take?
⚠ Common exam trap
Candidates often choose S3 Object Lambda for any processing, but it only acts on data retrieval. For upload-triggered processing, S3 event notification with Lambda is the standard serverless pattern.
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
✓
Use an S3 event notification to invoke a Lambda function that downloads the file, processes it, and uploads results.
S3 event notifications can trigger a Lambda function immediately after an object is uploaded. The Lambda function can download the file from S3, extract metadata and generate thumbnails, then store the results. This approach is serverless and cost-effective, as you pay only for compute time. While Lambda has execution time and memory limits, processing a 5 GB file for metadata and thumbnails can be optimized to fit within these limits, making it the most appropriate choice among the options.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use S3 Object Lambda to process the object as it is being retrieved.
Why it's wrong here
Wrong. S3 Object Lambda processes objects on GET requests (retrieval), not upon upload. For post-upload processing, you need a trigger like S3 event notifications.
- ✗
Use an S3 event notification to invoke a Lambda function that copies the object to an EC2 instance for processing.
Why it's wrong here
Wrong. Copying objects to an EC2 instance adds management overhead and cost, and EC2 instances run continuously even when idle, increasing expenses.
- ✗
Use AWS Fargate to run a container that polls S3 for new objects and processes them.
Why it's wrong here
Polling S3 for new objects introduces latency and unnecessary cost, as Fargate containers must run continuously or on a schedule, incurring compute charges even when no files arrive. This contrasts with an event-driven architecture using S3 Event Notifications to trigger processing instantly, which minimises idle time and cost. Fargate is tempting for long-running or stateful workloads, and would be correct if the application required persistent processing or custom runtimes beyond Lambda’s limits.
- ✓
Use an S3 event notification to invoke a Lambda function that downloads the file, processes it, and uploads results.
Why this is correct
Correct. S3 event notifications invoke a Lambda function directly when a new object is created. This allows processing the file in a serverless manner, minimizing cost and complexity. The Lambda function can efficiently handle the file by streaming and processing within its limits.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DVA-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 DVA-C02 exam.