DVA-C02 S3 Event Notifications Practice Question
A developer is building a serverless application that processes images uploaded to an S3 bucket. The processing includes generating thumbnails and storing metadata in DynamoDB. The developer wants to ensure that the processing function is triggered only when new objects are created, not when existing objects are updated. Which S3 event notification configuration should be used?
⚠ Common exam trap
The exam tests your knowledge of S3 event types. Candidates often mistakenly choose `s3:ObjectCreated:Put` thinking it covers all uploads. However, large files are often uploaded using multipart upload, which triggers `s3:ObjectCreated:CompleteMultipartUpload`, not `Put`. To capture all creation methods, `s3:ObjectCreated:*` must be used.
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 s3:ObjectCreated:*
The `s3:ObjectCreated:*` event type is a wildcard that covers all object creation APIs, including `s3:ObjectCreated:Put`, `s3:ObjectCreated:Post`, `s3:ObjectCreated:Copy`, and `s3:ObjectCreated:CompleteMultipartUpload`. Using `s3:ObjectCreated:*` ensures that the Lambda function is triggered regardless of how the image was uploaded or created in the bucket. If the developer only configured `s3:ObjectCreated:Put`, then images uploaded via multipart uploads (which trigger `CompleteMultipartUpload`) or POST requests would not trigger the function.
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:ObjectCreated:*
Why this is correct
Correct. s3:ObjectCreated:* captures all creation events, allowing the developer to filter updates in the processing function. While it does not exclusively trigger on new objects, it is the most comprehensive event type and is the intended answer given the limitations of S3 event notifications.
- ✗
Use s3:ObjectCreated:Post
Why it's wrong here
The s3:ObjectCreated:Post event specifically triggers when an object is uploaded using an HTTP POST request, typically originating from browser-based form uploads. While it signifies an object creation, this event type does not inherently distinguish between a truly new object and an overwrite of an existing object via a POST operation. Relying solely on `Post` would also miss objects uploaded through other common methods like `Put` or `Copy`, making it an incomplete solution for general new object detection.
- ✗
Use s3:ObjectCreated:Put
Why it's wrong here
The s3:ObjectCreated:Put event triggers whenever an object is uploaded or modified using an HTTP PUT request. This includes both the initial creation of a new object and the overwriting of an existing object with new content. Consequently, using `s3:ObjectCreated:Put` would not satisfy the requirement to trigger *only* when new objects are created, as it would also process updates to existing files, leading to unnecessary or incorrect processing.
- ✗
Use s3:ObjectCreated:Copy
Why it's wrong here
The s3:ObjectCreated:Copy event is exclusively triggered when an object is created in an S3 bucket as a result of a copy operation from another S3 object. This event type is too specific for the general requirement of processing newly uploaded images, as it would completely ignore objects created via direct PUT or POST uploads. Therefore, it fails to capture the primary mechanisms by which new images are typically introduced into the bucket.
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.