Quick Answer
The answer is to increase the function memory to 256 MB, as this is the most cost-effective fix for a Lambda function timeout. This works because AWS Lambda allocates CPU power proportionally to memory, so doubling the memory from 128 MB to 256 MB also doubles the available CPU performance, reducing execution time without needing to raise the timeout duration. Since Lambda billing is based on GB-seconds, a faster execution can keep total cost the same or even lower it, making this a smarter choice than simply increasing the timeout. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of Lambda’s resource allocation model and cost optimization—a common trap is to increase the timeout value, which only masks the problem and increases potential costs. Remember the memory tip: “More memory means more CPU, so faster runs can cut costs.”
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?
Increase the SQS batch size to 20
Why wrong: Larger batch sizes may increase processing time per invocation.
Increase the function timeout to 10 seconds
Why wrong: May not resolve the underlying performance issue.
Increase the function memory to 256 MB
More memory provides more CPU, reducing execution time.
Set reserved concurrency to 10
Why wrong: Reserved concurrency controls capacity, not performance.
Answer choices
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
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
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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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Incident and Event Response — study guide chapter
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FAQ
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
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 DevOps engineer is troubleshooting a Lambda function that processes S3 events. The function has been running successfully for months, but today it started timing out. The engineer checks CloudWatch Logs and sees 'Task timed out after 3.01 seconds' errors. The function is configured with a 3-second timeout. What should the engineer do to resolve the issue?
easyWhy C: Option C is correct because the function is timing out at the configured limit. Increasing the timeout to a higher value (e.g., 10 seconds) gives the function more time to complete. Option A is wrong because increasing memory may improve performance but does not directly address the timeout. Option B is wrong because the function already has a DLQ; the issue is the function timing out. Option D is wrong because the function is timing out, not provisioning limits.
Variation 2. A DevOps engineer is troubleshooting a Lambda function that is timing out. Which TWO actions should the engineer take to diagnose the issue?
easyWhy B: Option A is correct because increasing timeout may allow the function to complete. Option D is correct because CloudWatch Logs show execution details and errors. Option B is wrong because memory allocation doesn't directly affect timeout. Option C is wrong because VPC configuration is not directly related to timeout unless network issues. Option E is wrong because reserved concurrency affects scaling, not timeout.
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Last reviewed: Jun 24, 2026
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.
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