Question 1,400 of 724
DVA-C02 Troubleshooting and Optimization Practice Question
A developer is troubleshooting an AWS Lambda function that processes large CSV files (up to 1 GB) uploaded to an Amazon S3 bucket. The function uses Python and the pandas library to perform data transformations. Recently, the function started timing out on large files. CloudWatch Logs show that the function's execution time is close to the 15-minute Lambda timeout, and memory utilization peaks at around 80% of the configured 3,008 MB. The function has not been modified in months. Which action will most likely resolve the timeout issue without requiring code changes?
⚠ Common exam trap
Test-takers frequently assume the function needs more memory because memory utilization is at 80%, but the real bottleneck is CPU, which is tied to memory allocation in Lambda's pricing and performance model.
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
✓
Increase the memory allocation of the Lambda function to the maximum available (10,240 MB)
Increasing the memory allocation to the maximum (10,240 MB) proportionally increases the CPU and network throughput allocated to the Lambda function, which directly reduces execution time for CPU-bound pandas operations. Since memory utilization is only at 80% of the current 3,008 MB, the bottleneck is likely CPU, not memory, and Lambda's CPU scales linearly with memory configuration. This action resolves the timeout without any code changes.
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 memory allocation of the Lambda function to the maximum available (10,240 MB)
Why this is correct
Increasing the Lambda function's memory allocation directly scales the available CPU power, network bandwidth, and ephemeral storage. For CPU-intensive tasks like `pandas` processing of large CSV files, more CPU can significantly accelerate computations, reducing the overall execution time. This approach is highly effective in preventing timeouts by providing the necessary resources to complete the workload within the allowed duration, without requiring any changes to the existing function code.
- ✗
Increase the function timeout to the maximum allowed (900 seconds is already the max)
Why it's wrong here
The maximum execution timeout for an AWS Lambda function is a hard limit of 900 seconds (15 minutes). If the function is already consistently reaching this maximum timeout, it is impossible to extend it further, as there is no higher configurable value. Therefore, attempting to increase the timeout beyond 900 seconds is not a viable solution to resolve the function's execution failure.
- ✗
Use S3 Select to filter columns and rows before invoking the Lambda function
Why it's wrong here
While using S3 Select could effectively reduce the amount of data transferred and processed by the Lambda function, thereby potentially preventing timeouts, it fundamentally requires modifications to the existing Lambda function's code. The problem statement implies a constraint against code changes for troubleshooting, making S3 Select an unsuitable solution in this specific scenario. Implementing S3 Select involves altering the data retrieval logic within the function to leverage its filtering capabilities.
- ✗
Increase the batch size of the S3 event notification to invoke the function with multiple files
Why it's wrong here
Increasing the batch size for S3 event notifications primarily controls how many S3 object creation events are grouped and sent to the Lambda function in a single invocation request. However, this does not alter the Lambda function's internal logic, which is designed to process one large CSV file per invocation. The core issue of a single, large file exceeding execution limits remains unaddressed, as the function still dedicates its resources to that one file, irrespective of how many other file events were batched alongside it.
Visual reference
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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Same concept, more angles
1 more way this is tested on DVA-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A developer is troubleshooting an AWS Lambda function that is triggered by an S3 event. The function occasionally fails with a timeout error. CloudWatch logs show that the timeout occurs during the processing of large files. The function has a memory setting of 128 MB and a timeout of 3 seconds. The developer wants to process large files without modifying the code. Which parameter should the developer adjust first?
medium- ✓ A.Increase the function's memory
- B.Increase the function's timeout
- C.Increase the function's reserved concurrency
- D.Increase the S3 event notification batch size
Why A: Increasing the function's memory is the correct first step because Lambda allocates CPU proportionally to memory, and more CPU reduces processing time for CPU-bound tasks like decompressing or parsing large files. This directly addresses the timeout by making the function complete faster, without requiring code changes. The current 128 MB setting is the minimum, which provides the least CPU, so even a modest increase can significantly reduce execution time.
Last reviewed: Jun 11, 2026
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.
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