DEA-C01 Data Operations and Support Practice Question
A data engineer has set up an AWS Lambda function that processes files uploaded to an S3 bucket. The function is triggered by S3 event notifications. However, the function is not being invoked when a file is uploaded. The engineer checks the Lambda function's CloudWatch Logs and finds no execution logs. What should the engineer check FIRST?
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
✓
Verify that the S3 bucket has an event notification configured for the Lambda function.
The correct first step is to verify the S3 event notification configuration (Option C). Since there are no execution logs in CloudWatch, the Lambda function is not being triggered at all. This indicates a problem with the trigger mechanism, not with the function's code, permissions, or network configuration. Option A (checking code) is premature because code errors would appear in logs after invocation. Option B (IAM role) affects what the function can do during execution, not whether it is invoked. Option D (VPC) affects network access but does not prevent triggering. Therefore, the S3 bucket's event notification must be checked to ensure it is correctly set up to invoke the Lambda 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.
- ✗
Check the Lambda function's code for errors.
Why it's wrong here
Errors in code would appear in logs after invocation.
- ✗
Verify that the Lambda function's IAM role has permissions to read from S3.
Why it's wrong here
Permissions are for execution, not for triggering.
- ✓
Verify that the S3 bucket has an event notification configured for the Lambda function.
Why this is correct
Without event notification, S3 will not invoke the function.
- ✗
Check if the Lambda function is attached to a VPC.
Why it's wrong here
VPC configuration does not prevent invocation.
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 DEA-C01 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 DEA-C01 exam.