CV0-004 Deployment Practice Question
A cloud engineer needs to deploy a serverless function that runs when a new object is uploaded to an S3 bucket. Which AWS service event trigger should be configured?
⚠ Common exam trap
Candidates often confuse direct service integrations (S3 → Lambda) with event bus patterns (EventBridge), where they may overcomplicate by choosing EventBridge when the native S3 trigger is simpler and sufficient.
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
✓
S3
Amazon S3 can directly invoke AWS Lambda when a new object is uploaded by configuring an S3 event notification on the bucket. This native integration allows the S3 service to trigger the function without any intermediary service, making option C the correct choice for a serverless function triggered by an S3 upload event.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
API Gateway
Why it's wrong here
API Gateway triggers functions on HTTP requests, not on S3 object-upload events. It is tempting because it is a common serverless invocation path, but it exposes synchronous REST or WebSocket endpoints; an S3 object-created notification requires the S3 event source instead.
- ✗
EventBridge
Why it's wrong here
EventBridge routes events between services and supports S3 event patterns, but it is not the native trigger directly configured on the function for object-created notifications. It is tempting for complex event routing across accounts, yet the stem requires the direct S3 event source mapping.
- ✓
S3
Why this is correct
S3 emits event notifications when objects are created, so configuring an S3 event trigger invokes the serverless function on upload. This directly satisfies the requirement that the function runs when a new object lands in the bucket, without polling.
- ✗
SQS
Why it's wrong here
SQS is a polling queue, so it cannot push an event when an object lands in S3; the function would need to poll, adding latency and cost. It is tempting because SQS decouples producers from consumers, which suits buffering workloads, but S3 event notifications require a push-based trigger such as Lambda.
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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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.