Question 122 of 302
SAA-C03 Design High-Performing Architectures Practice Question
A system uses multiple AWS Lambda functions behind different event sources. One Lambda occasionally spikes and causes other Lambdas to be throttled due to shared concurrency limits. Which setting best helps ensure the important Lambda keeps capacity during spikes?
⚠ Common exam trap
It's easy for candidates to confuse Provisioned Concurrency (which reduces cold starts) with Reserved Concurrency (which guarantees capacity), leading candidates to pick Option C even though it does not solve the throttling issue.
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
✓
Set Reserved Concurrency for the important Lambda function.
Reserved Concurrency guarantees that the important Lambda function always has a set number of concurrent executions available, preventing other functions from consuming the account-level concurrency pool and throttling it during spikes. This setting isolates the function's capacity from shared contention, ensuring its performance remains stable.
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 function timeout so throttling is less likely.
Why it's wrong here
Timeout affects how long a request can run, not how many requests can run concurrently. Throttling is typically related to concurrency limits rather than time limits. Increasing timeout does not reserve capacity for another function.
- ✓
Set Reserved Concurrency for the important Lambda function.
Why this is correct
Reserved concurrency allocates a guaranteed amount of concurrent execution capacity to a specific Lambda. This prevents other functions from consuming all concurrency and throttling the important one. If the reserved limit is reached, only that function is throttled, isolating impact.
- ✗
Enable Provisioned Concurrency for every Lambda in the account.
Why it's wrong here
Provisioned Concurrency is useful for reducing cold starts, but it is not primarily a mechanism to guarantee capacity against account-wide spikes. Applying it to every function increases cost. Reserved concurrency is the direct control for prioritizing concurrency capacity.
- ✗
Reduce the number of IAM policies attached to the Lambda roles.
Why it's wrong here
IAM policy count does not control Lambda concurrency throttling. Throttling behavior depends on concurrency limits, scaling, and provisioned settings. Reducing IAM complexity improves manageability, not runtime concurrency availability.
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 |
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Last reviewed: Jun 11, 2026
This SAA-C03 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 SAA-C03 exam.
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