- A
Increase the SQS batch size to 20
Why wrong: Larger batch sizes may increase processing time per invocation.
- B
Increase the function timeout to 10 seconds
Why wrong: May not resolve the underlying performance issue.
- C
Increase the function memory to 256 MB
More memory provides more CPU, reducing execution time.
- D
Set reserved concurrency to 10
Why wrong: Reserved concurrency controls capacity, not performance.
Question 1,099 of 1,750
DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A DevOps engineer is troubleshooting an AWS Lambda function that is intermittently timing out. The function is configured with a 3-second timeout and 128 MB memory. The function processes messages from an SQS queue. What is the most cost-effective change to reduce timeouts?
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 function memory to 256 MB
Increasing the memory to 256 MB is the most cost-effective change because Lambda allocates CPU proportionally to memory, so doubling the memory from 128 MB to 256 MB also doubles the CPU performance. This reduces execution time, which can resolve timeouts without increasing the timeout duration, and since Lambda billing is based on compute time (GB-seconds), the total cost may stay the same or even decrease if the function finishes faster.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 SQS batch size to 20
Why it's wrong here
Larger batch sizes may increase processing time per invocation.
- ✗
Increase the function timeout to 10 seconds
Why it's wrong here
May not resolve the underlying performance issue.
- ✓
Increase the function memory to 256 MB
Why this is correct
More memory provides more CPU, reducing execution time.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set reserved concurrency to 10
Why it's wrong here
Reserved concurrency controls capacity, not performance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume increasing the timeout is the only way to fix timeouts, but AWS explicitly recommends increasing memory as a cost-effective performance tuning method because it also increases CPU, which can reduce execution time and thus avoid timeouts without increasing cost.
Detailed technical explanation
How to think about this question
Lambda's CPU allocation scales linearly with memory from 128 MB (baseline) up to 10,240 MB, with a proportional share of vCPU cycles. For CPU-bound tasks like parsing or transforming SQS messages, doubling memory often cuts execution time by more than half due to reduced CPU contention, making it a cost-effective tuning strategy. In practice, a 128 MB function timing out at 3 seconds might complete in under 1.5 seconds at 256 MB, keeping the total cost similar or lower because the reduced duration offsets the higher memory price.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
Visual reference
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Incident and Event Response — study guide chapter
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FAQ
Questions learners often ask
What does this DOP-C02 question test?
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the function memory to 256 MB — Increasing the memory to 256 MB is the most cost-effective change because Lambda allocates CPU proportionally to memory, so doubling the memory from 128 MB to 256 MB also doubles the CPU performance. This reduces execution time, which can resolve timeouts without increasing the timeout duration, and since Lambda billing is based on compute time (GB-seconds), the total cost may stay the same or even decrease if the function finishes faster.
What should I do if I get this DOP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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