DOP-C02 Resilient Cloud Solutions Practice Question
A company runs a serverless application using AWS Lambda functions behind an Amazon API Gateway. The application processes user uploads stored in an S3 bucket. The Lambda function writes results to a DynamoDB table. Recently, the function started timing out when processing large files. What should the DevOps engineer do to improve resilience for large file processing?
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 event notifications to trigger an AWS Step Functions workflow that processes the file asynchronously.
Using S3 event notifications to trigger an AWS Step Functions workflow enables asynchronous processing of large files, decoupling the upload from the processing and avoiding Lambda's timeout limits. Option A (increasing memory) may improve CPU performance but does not address the timeout issue for large files. Option C (increasing timeout) can extend up to 15 minutes, but large files may still exceed this limit and it does not provide a resilient architecture. Option D (ElastiCache) caches processed results but does not solve the initial timeout problem; it is irrelevant to the large file processing issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the Lambda function memory to improve CPU performance.
Why it's wrong here
More memory scales CPU proportionally but does not remove the 15-minute ceiling or API Gateway's 29-second integration timeout, so large uploads still fail. It is tempting because CPU-bound functions speed up, and it would be correct for compute-heavy work that already finishes within the invocation limit.
- ✓
Use S3 event notifications to trigger an AWS Step Functions workflow that processes the file asynchronously.
Why this is correct
S3 event notifications triggering Step Functions decouple processing from the API request, letting large files be handled asynchronously with retries and state tracking. This removes the Lambda timeout constraint imposed by synchronous invocation behind API Gateway.
- ✗
Increase the Lambda function timeout to the maximum 15 minutes.
Why it's wrong here
Raising the timeout merely lets the same synchronous invocation run longer, so large files still exceed API Gateway's 29-second integration limit and the request fails. It is tempting because timeouts are the visible symptom, and it would help for asynchronous batch jobs with no gateway in front.
- ✗
Add Amazon ElastiCache to cache processed results and reduce Lambda execution time.
Why it's wrong here
ElastiCache stores results but does not change how the Lambda reads and processes each large file, so first-pass executions still time out. It is tempting because caching reduces repeated work, and it would be correct for read-heavy workloads with recurring identical queries rather than one-off large-file processing.
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 DOP-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 DOP-C02 exam.