Question 663 of 1,040
Design High-Performing ArchitectureshardMultiple SelectObjective-mapped

Lambda Provisioned Concurrency to Eliminate Cold Starts

This SAA-C03 practice question tests your understanding of design high-performing architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 serverless checkout API runs on AWS Lambda behind API Gateway. Traffic spikes are predictable every weekday at 09:00 UTC, and p95 latency jumps for the first few minutes after each deployment because execution environments are cold. The team wants to reduce this startup impact without changing the API contract. Which changes should they make? Select three.

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "first"

    Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

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

Configure provisioned concurrency on the production Lambda alias during the busy windows.

Provisioned concurrency initializes a specified number of execution environments in advance, so when traffic spikes at 09:00 UTC, the Lambda function is already warm and can serve requests without cold start latency. This directly addresses the p95 latency jump after deployment without altering the API contract.

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.

  • Configure provisioned concurrency on the production Lambda alias during the busy windows.

    Why this is correct

    Correct. Provisioned concurrency keeps a pool of pre-initialized execution environments ready to handle invocations, which directly reduces cold-start latency. Using an alias allows the team to manage production traffic separately from development or canary versions and to schedule capacity for the predictable weekday peak.

    Clue confirmation

    The clue word "first" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Initialize SDK clients and other reusable objects outside the handler so they are created once per execution environment.

    Why this is correct

    Correct. Code that runs outside the handler executes during environment initialization and is then reused for subsequent invocations in the same execution environment. Reusing database clients, SDK clients, connection pools, and compiled configuration reduces per-invocation setup time and lowers the first-request penalty.

    Clue confirmation

    The clue word "first" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Reduce the deployment package size and remove unnecessary layers to shorten function initialization.

    Why this is correct

    Correct. Smaller packages and fewer dependencies generally reduce code download, unzip, and runtime initialization overhead. Trimming unused libraries and layers reduces the work required when Lambda creates a new execution environment after deployment or scale-out.

    Clue confirmation

    The clue word "first" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Replace provisioned concurrency with reserved concurrency because reserved concurrency keeps instances warm.

    Why it's wrong here

    Incorrect. Reserved concurrency only sets an upper limit and optionally reserves capacity for a function; it does not pre-warm execution environments. Provisioned concurrency is the feature that initializes environments in advance to reduce cold starts.

  • Increase the function timeout so the first request has more time to warm up.

    Why it's wrong here

    Incorrect. Timeout changes how long Lambda waits before it fails an invocation, but it does not reduce initialization time or improve the p95 latency experienced by the caller. The issue is startup overhead, not insufficient execution time.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is confusing reserved concurrency (which only limits concurrency) with provisioned concurrency (which pre-warms instances), leading candidates to incorrectly select reserved concurrency as a solution for cold starts.

Detailed technical explanation

How to think about this question

Provisioned concurrency works by keeping a set number of execution environments initialized and ready to handle requests, effectively eliminating cold start latency for those instances. Under the hood, AWS Lambda pre-allocates resources and runs the initialization code (outside the handler) so that when a request arrives, the handler executes immediately. This is especially useful for predictable traffic patterns, as the cost is incurred for the provisioned instances even when idle.

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.

Quick reference

Cloud Service Model Comparison

ModelYou ManageProvider ManagesExamples
IaaSOS, runtime, apps, dataHardware, hypervisor, networkingEC2, Azure VMs, GCP Compute Engine
PaaSApps and dataOS, runtime, middleware, hardwareElastic Beanstalk, Azure App Service
SaaSData and settings onlyEverything elseMicrosoft 365, Salesforce, Workday
FaaS / ServerlessFunction code onlyInfra, scaling, runtimeLambda, Azure Functions, Cloud Run
CaaSContainers and appsKubernetes, OS, hardwareEKS, 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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FAQ

Questions learners often ask

What does this SAA-C03 question test?

Design High-Performing Architectures — This question tests Design High-Performing Architectures — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Configure provisioned concurrency on the production Lambda alias during the busy windows. — Provisioned concurrency initializes a specified number of execution environments in advance, so when traffic spikes at 09:00 UTC, the Lambda function is already warm and can serve requests without cold start latency. This directly addresses the p95 latency jump after deployment without altering the API contract.

What should I do if I get this SAA-C03 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

5 more ways this is tested on SAA-C03

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 Lambda-based retail API has unpredictable traffic spikes and users see latency caused by cold starts. The function must respond consistently during expected campaign windows. What should be configured? The design must avoid adding custom operational scripts.

hard
  • A.A larger deployment package
  • B.Reserved concurrency only
  • C.Provisioned concurrency during campaign windows
  • D.CloudTrail data events

Why C: Provisioned concurrency initializes a specified number of execution environments in advance, eliminating cold starts during campaign windows. This ensures consistent response times for the Lambda-based retail API under unpredictable traffic spikes without requiring custom scripts.

Variation 2. A Lambda-based retail API has unpredictable traffic spikes and users see latency caused by cold starts. The function must respond consistently during expected campaign windows. What should be configured?

hard
  • A.A larger deployment package
  • B.Reserved concurrency only
  • C.Provisioned concurrency during campaign windows
  • D.CloudTrail data events

Why C: Provisioned concurrency initializes a specified number of execution environments in advance, eliminating cold starts during campaign windows. This ensures consistent latency even under unpredictable traffic spikes, as the function is always warm and ready to handle requests immediately.

Variation 3. A Lambda-based retail API has unpredictable traffic spikes and users see latency caused by cold starts. The function must respond consistently during expected campaign windows. What should be configured? The architecture review board prefers a managed AWS-native control.

hard
  • A.A larger deployment package
  • B.Reserved concurrency only
  • C.Provisioned concurrency during campaign windows
  • D.CloudTrail data events

Why C: Provisioned concurrency pre-warms a specified number of Lambda execution environments, eliminating cold starts during the campaign windows. This is a managed AWS-native feature that ensures consistent sub-100ms response times even under unpredictable traffic spikes, directly addressing the latency issue.

Variation 4. A serverless checkout API uses AWS Lambda behind API Gateway. Every weekday at 09:00 UTC, marketing triggers a predictable surge. The first few minutes after each surge show cold-start latency, but traffic volume is forecastable and the business wants stable p95 latency. Which two changes should the team implement? Select two.

hard
  • A.Publish a Lambda version and attach provisioned concurrency to an alias that points to that version.
  • B.Use Application Auto Scaling scheduled actions to raise provisioned concurrency before 09:00 UTC and lower it afterward.
  • C.Increase the Lambda timeout so the function has more time to initialize during the spike.
  • D.Double the memory size during the spike without changing the concurrency model.
  • E.Move the function into more Availability Zones so the platform can spread cold starts across regions.

Why A: Provisioned concurrency keeps a specified number of Lambda execution environments initialized and ready to respond immediately, eliminating cold starts for predictable traffic patterns. By publishing a Lambda version and attaching provisioned concurrency to an alias pointing to that version, the team ensures that the surge at 09:00 UTC is handled without cold-start latency, stabilizing p95 latency.

Variation 5. A Lambda function behind an API needs consistent low latency. Traffic normally drops to near zero, then spikes several times per hour. During spikes, the p95 latency often spikes above 800 ms due to cold starts. The team wants to keep using Lambda (no containers) but minimize cold start impact during predictable spikes. What is the best AWS configuration to meet this goal?

medium
  • A.Enable Lambda provisioned concurrency on a published function alias and set the minimum provisioned instances to the baseline expected during spikes.
  • B.Increase the function memory size to the maximum and rely on the larger memory to eliminate cold starts.
  • C.Configure an ALB with target group health checks to keep Lambda warm by sending periodic requests.
  • D.Turn on AWS CloudTrail data events to monitor cold start frequency and tune the runtime accordingly.

Why A: Provisioned concurrency initializes a specified number of execution environments in advance, keeping them warm and ready to handle requests instantly. By setting the minimum provisioned instances to the baseline expected during spikes, the function avoids cold starts for those requests, ensuring p95 latency stays low even when traffic surges from near zero.

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Last reviewed: Jun 11, 2026

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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.