Which AWS Service Best Fits a Sporadic Sub-5-Minute Application?

CLF-C02 By islever Editorial Last updated

Identify AWS compute services. Compare AWS pricing models.

Short answer

B AWS Lambda is most cost-effective because it bills only for invocation time and scales to zero for sporadic, sub-5-minute workloads.

Question

A company has an on-premises application. The application has processing times of less than 5 minutes and is invoked only a few times each day. The company wants to move the application to the AWS Cloud. Which AWS service will support this application MOST cost-effectively?
  1. Amazon Elastic Container Service (Amazon ECS)
  2. AWS Lambda Correct Answer
  3. Amazon Elastic Kubernetes Service (Amazon EKS)
  4. Amazon EC2

Key Takeaways

The exam is testing serverless compute selection for intermittent, short-duration work; the trap is picking a container or instance service that stays provisioned and bills for idle time.

This question tests whether you can match a sporadically invoked, short-running on-premises workload to the most cost-effective AWS compute service. AWS Lambda wins because it bills per invocation and scales to zero, unlike ECS, EKS, or EC2, which keep capacity running between calls.

Common mistake: Many learners choose Amazon EC2 because it is the most familiar compute option, but a fleet of instances bills hourly even when the application is invoked only a few times a day.

Expert Analysis

Why the Answer Is Correct

AWS Lambda is the only option here that charges strictly for compute duration per invocation, so an application invoked a few times daily with sub-5-minute processing costs almost nothing. Lambda also removes server provisioning and patching, so the company pays no idle capacity between the sporadic calls. Because Lambda's maximum timeout is 15 minutes, a processing time under 5 minutes sits comfortably inside the supported limit. That combination of event-driven scaling and per-millisecond billing is exactly what the cost-effectiveness requirement is pointing to.

Why the Other Options Are Wrong

Amazon ECS (A) and Amazon EKS (C) are container orchestrators that require you to run and pay for the underlying compute capacity, typically through EC2 instances or Fargate tasks, and they add control-plane or cluster management overhead that a few daily invocations do not justify. Amazon EC2 (D) bills per running instance-hour, so a server kept available for occasional calls is idle and wasteful, and it also carries patching and operational responsibility. None of these three can scale to zero on their own while remaining instantly callable the way Lambda does.

Community Comment Notes

Every learner vote recorded here converges on Lambda, and samosa_123 frames it well: Lambda "charges you only for the compute time used," which is precisely the cost argument the question asks for. Nikmah adds the event-driven dimension, noting that Lambda functions "get invoked by AWS when needed," which matches the sporadic invocation pattern. ShaiTay and d00b229 simply confirm the same choice, so there is no meaningful dissent to weigh against the technical reasoning.

Official Reference

These links open the official vendor documentation in a new tab.

Exam Strategy

When a stem emphasizes sporadic invocations, short runtimes, and cost-effectiveness, scan first for AWS Lambda before considering any container or instance service. Memorize Lambda's 15-minute maximum timeout, because that number quickly disqualifies or confirms Lambda on CLF-C02 questions.

Frequently Asked Questions

Why isn't Amazon ECS the cost-effective choice for a few daily invocations?

ECS needs underlying compute capacity that stays provisioned for the cluster, so you pay for idle time between the few daily calls, unlike Lambda's per-invocation billing.

Does Lambda's 15-minute timeout matter for this application?

Yes. Processing under 5 minutes fits well inside Lambda's 15-minute maximum, which confirms Lambda is a valid fit rather than a constraint here.

More CLF-C02 FAQ →

Community Votes

B
100%

100% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

  1. samosa_123 👍 3 Answered B
    B. AWS Lambda: AWS Lambda is a serverless compute service that charges you only for the compute time used. Since the application is invoked only a few times each day and has short processing times (less than 5 minutes), Lambda is the most cost-effective option. You don't need to manage any infrastructure, and you only pay for the time your code is running.
  2. Nikmah 👍 1 Answered B
    benefit lambda : • Event-Driven: functions get invoked by AWS when needed
  3. ShaiTay 👍 1 Answered B
    B. AWS Lambda

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