DVA-C02 Deployment Practice Question
A developer is deploying a Lambda function that processes images uploaded to an S3 bucket. The function is triggered by S3 events. After deployment, the function does not execute when new images are uploaded. What is the MOST likely cause?
⚠ Common exam trap
Many exam-takers confuse the trigger configuration (S3 event notification) with the function's permissions (IAM execution role), assuming that if the function has read access to S3, it will automatically be triggered, when in fact the event notification is a separate, mandatory setup step.
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
✓
The S3 bucket does not have an event notification configured for the Lambda function.
The most likely cause is that the S3 bucket does not have an event notification configured to invoke the Lambda function. S3 event notifications must be explicitly set on the bucket to trigger a Lambda function when objects are created; without this configuration, S3 will not send any invocation request to Lambda, regardless of the function's permissions or settings.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The S3 bucket does not have an event notification configured for the Lambda function.
Why this is correct
For an AWS Lambda function to be automatically invoked in response to an S3 object event, such as an image upload, the S3 bucket must have a specific event notification configured. This configuration explicitly links the desired S3 event type (e.g., s3:ObjectCreated:*) to the target Lambda function. Without this crucial setup, S3 will not know to send an invocation request to the Lambda service, preventing the function from ever being triggered.
- ✗
The Lambda function memory is set too low.
Why it's wrong here
While insufficient memory can severely impact a Lambda function's execution, leading to performance degradation, timeouts, or even invocation failures during runtime, it does not prevent the function from being triggered in the first place. The S3 event notification mechanism would still successfully invoke the Lambda service; the issue would manifest only once the function attempts to allocate resources and execute its code. Therefore, low memory is an execution-time problem, not a trigger-time problem.
- ✗
The Lambda function does not have permission to read from the S3 bucket.
Why it's wrong here
The permissions for a Lambda function to read from an S3 bucket are governed by its IAM execution role. If these permissions are missing, the function would still be successfully triggered by the S3 event notification. However, upon execution, when the function attempts to access the S3 object, it would encounter an AccessDenied error and fail. This is an execution-time authorization issue, distinct from the initial trigger mechanism.
- ✗
The Lambda function is not in the same region as the S3 bucket.
Why it's wrong here
Although direct S3 event notifications to a Lambda function typically require both resources to reside within the same AWS region, this is not an absolute barrier to all cross-region triggering. More complex architectures, such as using an SQS queue or SNS topic in the S3 bucket's region to forward events to a Lambda function in a different region, are entirely possible. Therefore, the region difference alone doesn't inherently prevent any form of triggering, making the missing notification configuration the more fundamental and direct cause of the problem.
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 |
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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.