- A
High availability
Why wrong: Incorrect. High availability focuses on ensuring a system remains operational and accessible despite component failures (e.g., using redundancy). It does not directly address automatically adjusting capacity to match fluctuating demand.
- B
Fault tolerance
Why wrong: Incorrect. Fault tolerance is the ability of a system to continue functioning correctly even when some of its components fail. The scenario is about handling variable demand, not component failures.
- C
Scalability
Why wrong: Incorrect but plausible. Scalability is the capacity to handle increased load by adding resources. However, scalability does not inherently imply automatic scaling up and down. It can be manual or planned. Elasticity is the more precise term for automatic, dynamic scaling based on demand.
- D
Elasticity
Correct. Elasticity is the cloud characteristic that allows resources to be automatically provisioned and de-provisioned in real time to match current demand. The automatic addition and removal of VMs in response to variable traffic directly demonstrates elasticity, which helps manage costs by only paying for what is used.
Quick Answer
The answer is elasticity. Elasticity is the correct choice because it describes a cloud system’s ability to automatically provision and de-provision resources—like virtual machines—in real time to match fluctuating demand, which directly supports the goal of handling variable traffic efficiently while minimizing cost. In the AZ-900 exam, this concept tests your understanding of how Azure’s autoscaling features, such as Virtual Machine Scale Sets, enable resources to scale out during sudden spikes and scale in during low usage without manual intervention. A common trap is confusing elasticity with scalability: scalability is the ability to handle growth over time, while elasticity specifically addresses automatic, real-time adjustments to changing demand. Remember the memory tip: “Elasticity stretches and snaps back automatically,” just like a rubber band responding to pressure.
AZ-900 Describe cloud concepts Practice Question
This AZ-900 practice question tests your understanding of describe cloud concepts. 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 retail company runs an e-commerce website on Azure. The website experiences highly unpredictable traffic with occasional sudden spikes (e.g., during flash sales). Outside of sales events, the website has low traffic. The company wants to automatically increase the number of virtual machines during peak demand and automatically reduce them when demand subsides, without any manual intervention. The primary goal is to handle variable demand efficiently while minimizing cost. Which cloud computing characteristic best describes this capability?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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
Elasticity
Elasticity is the correct answer because it specifically refers to the ability of a cloud system to automatically provision and de-provision resources (such as virtual machines) in response to real-time demand changes. In this scenario, the e-commerce website needs to scale out during flash sales and scale in during low traffic periods without manual intervention, which is the defining characteristic of elasticity. This capability directly supports the goal of handling variable demand efficiently while minimizing cost, as resources are only consumed when needed.
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.
- ✗
High availability
Why it's wrong here
Incorrect. High availability focuses on ensuring a system remains operational and accessible despite component failures (e.g., using redundancy). It does not directly address automatically adjusting capacity to match fluctuating demand.
- ✗
Fault tolerance
Why it's wrong here
Incorrect. Fault tolerance is the ability of a system to continue functioning correctly even when some of its components fail. The scenario is about handling variable demand, not component failures.
- ✗
Scalability
Why it's wrong here
Incorrect but plausible. Scalability is the capacity to handle increased load by adding resources. However, scalability does not inherently imply automatic scaling up and down. It can be manual or planned. Elasticity is the more precise term for automatic, dynamic scaling based on demand.
- ✓
Elasticity
Why this is correct
Correct. Elasticity is the cloud characteristic that allows resources to be automatically provisioned and de-provisioned in real time to match current demand. The automatic addition and removal of VMs in response to variable traffic directly demonstrates elasticity, which helps manage costs by only paying for what is used.
Clue confirmation
The clue words "best", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'scalability' (the ability to handle growth) with 'elasticity' (the ability to automatically and dynamically adjust resources in real time), but the question's emphasis on automatic, demand-driven scaling and cost minimization points specifically to elasticity.
Trap categories for this question
Scenario analysis trap
Incorrect. Fault tolerance is the ability of a system to continue functioning correctly even when some of its components fail. The scenario is about handling variable demand, not component failures.
Detailed technical explanation
How to think about this question
Under the hood, Azure implements elasticity through features like Virtual Machine Scale Sets (VMSS) with autoscale rules based on metrics such as CPU percentage or queue depth, and Azure Functions for serverless compute. A subtle behavior is that elasticity can be horizontal (adding/removing VMs) or vertical (resizing VMs), but horizontal scaling is typically preferred for stateless web tiers because it avoids downtime and allows granular cost control. In a real-world scenario, a flash sale might trigger autoscale to add 50 VMs within minutes, then scale back to 2 VMs after the event, ensuring the company only pays for the extra capacity during the spike.
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.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this AZ-900 question test?
Describe cloud concepts — This question tests Describe cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Elasticity — Elasticity is the correct answer because it specifically refers to the ability of a cloud system to automatically provision and de-provision resources (such as virtual machines) in response to real-time demand changes. In this scenario, the e-commerce website needs to scale out during flash sales and scale in during low traffic periods without manual intervention, which is the defining characteristic of elasticity. This capability directly supports the goal of handling variable demand efficiently while minimizing cost, as resources are only consumed when needed.
What should I do if I get this AZ-900 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: "best", "primary". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on AZ-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. A retail company runs its e-commerce platform on Azure App Service. The platform is configured with an autoscale rule that adds web server instances when CPU usage exceeds 75%. During a holiday flash sale, traffic surges from a baseline of 1,000 concurrent users to over 100,000 concurrent users within minutes. The platform automatically provisions additional instances to handle the load, and once the sale ends, it scales back down. This ability to rapidly adjust resources to meet varying demand is a direct example of which fundamental characteristic of cloud computing?
medium- A.On-demand self-service
- ✓ B.Rapid elasticity
- C.Measured service
- D.Resource pooling
Why B: Rapid elasticity is the cloud characteristic that enables resources to scale out (add instances) and scale in (remove instances) automatically and quickly in response to demand changes. In this scenario, the autoscale rule on Azure App Service detects CPU usage exceeding 75% and provisions additional web server instances within minutes to handle the surge from 1,000 to over 100,000 concurrent users, then scales back down after the flash sale ends. This dynamic, near-instantaneous adjustment of capacity is the direct embodiment of rapid elasticity, distinguishing it from manual provisioning or fixed capacity models.
Last reviewed: Jun 11, 2026
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.
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