MS-900 Describe cloud concepts Practice Question
An e-commerce website hosted on a cloud provider automatically adds more virtual machines to handle increased traffic during Black Friday and removes them after the event. Which cloud characteristic does this illustrate?
⚠ Common exam trap
Candidates often confuse 'rapid elasticity' with 'on-demand self-service' because both involve automation, but elasticity specifically refers to automatic scaling in response to load, not just the ability to provision resources on demand.
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
✓
Rapid elasticity
Rapid elasticity is the cloud characteristic that enables resources to scale out (add VMs) automatically in response to demand spikes like Black Friday traffic, and scale in (remove VMs) when demand subsides. This is distinct from manual scaling because it happens automatically and dynamically, often using autoscaling policies tied to metrics such as CPU utilization or request count.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Rapid elasticity
Why this is correct
Rapid elasticity is the correct NIST characteristic because it enables the cloud to automatically provision and release compute resources—such as VMs—in response to fluctuating demand. In this scenario, the e-commerce site's traffic spikes trigger an immediate increase in VM instances, and when traffic subsides, those instances are automatically deprovisioned, making the resource pool appear infinite and highly responsive.
- ✗
On-demand self-service
Why it's wrong here
On-demand self-service is incorrect because it refers to a user or customer manually provisioning cloud resources, such as spinning up a VM through a web portal or API, without requiring human interaction with the provider. The automatic scaling described in the question is initiated by system monitoring and load thresholds, not by a user request, so it does not represent self-service provisioning.
- ✗
Resource pooling
Why it's wrong here
Resource pooling is incorrect because it describes the provider's ability to serve multiple customers from a shared pool of physical and virtual resources that can be dynamically assigned and reassigned according to demand. While this sharing underpins multi-tenancy, it is a static infrastructure characteristic; it does not explain the automatic, customer-visible scaling of VMs that the e-commerce site experiences during traffic spikes.
- ✗
Measured service
Why it's wrong here
Measured service is incorrect because it involves the cloud provider metering and monitoring resource usage—such as CPU hours, storage, or bandwidth—for purposes of billing, usage reporting, and cost optimization. Although automatic scaling may affect measured usage, the measured service characteristic itself does not drive or describe the elastic scaling behavior; it simply tracks the consumption that results from that scaling.
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Same concept, more angles
1 more way this is tested on MS-900
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. An e-commerce application runs in the cloud and automatically adjusts the number of virtual machines based on real-time traffic. When traffic spikes, more VMs are added; when traffic drops, VMs are removed. Which cloud computing characteristic does this behavior exemplify?
medium- ✓ A.Rapid elasticity
- B.Measured service
- C.Resource pooling
- D.On-demand self-service
Why A: Rapid elasticity is the cloud characteristic that enables resources to scale out (add VMs) and scale in (remove VMs) automatically in response to real-time demand. In this e-commerce scenario, the application adjusts VM count based on traffic spikes and drops, which directly matches the definition of rapid elasticity as defined by NIST SP 800-145.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MS-900 practice question is part of Courseiva's free Microsoft 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 MS-900 exam.