AZ-900 Describe cloud concepts Practice Question
A company runs an e-commerce web application on a set of Azure virtual machines behind a load balancer. The application experiences unpredictable traffic surges during flash sales. The company configures an autoscale setting that automatically adds virtual machines when the average CPU usage across the existing VMs exceeds 75% for five minutes, and removes virtual machines when CPU usage drops below 30% for ten minutes. Which essential characteristic of cloud computing does this configuration primarily demonstrate?
⚠ Common exam trap
Many candidates confuse rapid elasticity with measured service because both involve resource usage, but measured service is about billing and monitoring usage, not the ability to dynamically scale resources up or down.
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
B is correct because the autoscale configuration dynamically adds and removes virtual machines in response to real-time CPU usage thresholds, which is the defining characteristic of rapid elasticity. This allows the e-commerce application to scale computing resources up and down automatically and seamlessly to match unpredictable traffic surges, ensuring performance during flash sales without manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Measured service
Why it's wrong here
Measured service means that cloud providers meter and report resource usage for billing and optimization. While usage is measured in autoscaling, the primary characteristic demonstrated is the ability to scale dynamically, not the metering aspect.
When this WOULD be correct
A question where the company uses Azure Monitor to track VM CPU usage and generates detailed billing reports based on resource consumption, asking which cloud characteristic enables pay-per-use billing.
- ✓
Rapid elasticity
Why this is correct
Rapid elasticity is the correct answer because the autoscale configuration automatically adds and removes virtual machines based on CPU demand, enabling the system to elastically scale outward and inward. This is a core characteristic of cloud computing defined by NIST.
- ✗
Resource pooling
Why it's wrong here
Resource pooling describes the cloud provider's physical and virtual compute resources being pooled to serve multiple tenants on a shared infrastructure, with location independence and no direct control over the underlying hardware. The scenario focuses on a single e-commerce application whose virtual machine count changes automatically based on CPU utilization, which is a scaling action rather than a demonstration of multi-tenant pooling. Because no multi-tenant or infrastructure-sharing aspect is mentioned, this option is not the characteristic being exhibited.
When this WOULD be correct
A question describing how a cloud provider uses virtualization to serve multiple customers from the same physical hardware, with customers having no knowledge or control over the exact location of their resources, would make resource pooling the correct answer.
- ✗
Broad network access
Why it's wrong here
Broad network access is a NIST cloud characteristic that means resources are reachable over standard network protocols (for example, HTTPS, RDP, or SSH) from heterogeneous client platforms. In this scenario, the key behavior is the autoscale configuration adding and removing virtual machines in response to CPU demand, which illustrates dynamic capacity adjustment, not how clients connect to the service. Therefore, while Azure VMs are certainly network-accessible, this option does not explain the specific mechanism described in the question.
When this WOULD be correct
A question that asks which cloud characteristic enables users to access resources from various devices (e.g., laptops, smartphones, tablets) using standard network protocols (e.g., HTTP, HTTPS) would have broad network access as the correct answer. For example: 'A company allows employees to access cloud storage from their mobile phones and laptops. Which cloud characteristic does this demonstrate?'
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Rapid elasticityCorrect answer▾
Why this is correct
Rapid elasticity is the correct answer because the autoscale configuration automatically adds and removes virtual machines based on CPU demand, enabling the system to elastically scale outward and inward. This is a core characteristic of cloud computing defined by NIST.
✗Measured serviceWrong answer — click to see why▾
Why this is wrong here
Measured service refers to the ability to monitor and report resource usage for billing or optimization, but the scenario describes automatic scaling based on demand, which is rapid elasticity.
★ When this WOULD be the correct answer
A question where the company uses Azure Monitor to track VM CPU usage and generates detailed billing reports based on resource consumption, asking which cloud characteristic enables pay-per-use billing.
Why candidates choose this
Candidates may confuse autoscaling with metering because both involve monitoring metrics, but measured service is about usage tracking and billing, not dynamic resource adjustment.
✗Resource poolingWrong answer — click to see why▾
Why this is wrong here
Resource pooling refers to the provider's computing resources being pooled to serve multiple customers, with physical and virtual resources dynamically assigned according to demand. This question focuses on the ability to rapidly scale resources up and down based on demand, which is rapid elasticity, not the multi-tenant pooling of resources.
★ When this WOULD be the correct answer
A question describing how a cloud provider uses virtualization to serve multiple customers from the same physical hardware, with customers having no knowledge or control over the exact location of their resources, would make resource pooling the correct answer.
Why candidates choose this
Candidates may confuse resource pooling with elasticity because both involve dynamic resource allocation, but resource pooling is about multi-tenancy and location independence, not scaling in response to demand.
✗Broad network accessWrong answer — click to see why▾
Why this is wrong here
Broad network access refers to the ability to access cloud resources over the network via standard protocols, not to the automatic scaling of resources based on demand. The scenario describes scaling VMs in response to CPU usage, which is about rapid elasticity, not network access.
★ When this WOULD be the correct answer
A question that asks which cloud characteristic enables users to access resources from various devices (e.g., laptops, smartphones, tablets) using standard network protocols (e.g., HTTP, HTTPS) would have broad network access as the correct answer. For example: 'A company allows employees to access cloud storage from their mobile phones and laptops. Which cloud characteristic does this demonstrate?'
Why candidates choose this
Candidates might confuse 'broad network access' with the idea that the autoscale configuration relies on network monitoring or that scaling involves network resources, but the term specifically refers to ubiquitous network access, not scaling.
Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
What is Cloud Computing?
Key term
Elasticity
Elasticity is the ability of a cloud system to automatically add or remove computing resources (like servers, storage, or bandwidth) in response to real-time changes in demand.
Key term
Cloud computing
Cloud computing is the on-demand delivery of IT resources over the internet, allowing users to access computing power, storage, and applications without owning physical hardware.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-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 AZ-900 exam.