- A
Elasticity
Correct. Elasticity is the cloud characteristic that enables resources to be automatically added or removed in response to real-time demand, allowing the application to handle traffic spikes and then scale back down to optimize costs.
- B
Scalability
Why wrong: Scalability is the ability to increase capacity to handle growing demand, but it does not inherently imply automatic scaling down. Elasticity includes both scaling up and down dynamically, which is the key difference in this scenario.
- C
High availability
Why wrong: High availability ensures that the application remains accessible despite component failures through redundancy (e.g., multiple instances in different zones). This scenario focuses on load-driven scaling, not failure recovery.
- D
Fault tolerance
Why wrong: Fault tolerance refers to the ability of a system to continue operating without interruption when one or more components fail. The scenario describes scaling in response to demand, not handling component failures.
Quick Answer
The answer is elasticity. This is the correct choice because elasticity specifically refers to the ability to dynamically provision and de-provision cloud resources—like Azure App Service instances—in real time to match fluctuating demand, as seen when the marketing campaign triggers a fivefold traffic surge and the system automatically adds then removes instances. Scalability, by contrast, is the broader capacity to handle growth, but it often involves planned, long-term scaling rather than the automatic, short-term response to spikes that defines elasticity. On the Microsoft Azure Fundamentals AZ-900 exam, this distinction is a frequent trap: many candidates confuse elasticity with scalability, but remember that elasticity is about reacting to real-time changes, while scalability is about meeting predictable growth. A common memory tip is to think of a rubber band—elasticity stretches and snaps back instantly, just like your cloud resources.
AZ-900 Describe cloud concepts Practice Question
This AZ-900 practice question tests your understanding of describe cloud concepts. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 company runs a web application on Azure App Service. During a marketing campaign, the application's traffic surges to five times its normal level. The application is configured to automatically add more instances to handle the increased load and then remove them when demand returns to normal. This ability to dynamically provision and de-provision resources based on real-time demand is a direct example of which cloud computing characteristic?
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
The scenario describes automatically adding and removing App Service instances in response to real-time traffic spikes, which is the definition of elasticity. Elasticity is the ability to dynamically scale resources up or down to match demand, ensuring you only pay for what you use. In Azure, this is implemented via autoscale rules that adjust the instance count based on metrics like CPU or request queue length.
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.
- ✓
Elasticity
Why this is correct
Correct. Elasticity is the cloud characteristic that enables resources to be automatically added or removed in response to real-time demand, allowing the application to handle traffic spikes and then scale back down to optimize costs.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Scalability
Why it's wrong here
Scalability is the ability to increase capacity to handle growing demand, but it does not inherently imply automatic scaling down. Elasticity includes both scaling up and down dynamically, which is the key difference in this scenario.
- ✗
High availability
Why it's wrong here
High availability ensures that the application remains accessible despite component failures through redundancy (e.g., multiple instances in different zones). This scenario focuses on load-driven scaling, not failure recovery.
- ✗
Fault tolerance
Why it's wrong here
Fault tolerance refers to the ability of a system to continue operating without interruption when one or more components fail. The scenario describes scaling in response to demand, not handling component failures.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse scalability (the ability to grow) with elasticity (the ability to both grow and shrink automatically), so they pick 'Scalability' without recognizing that the scenario explicitly mentions removing resources when demand returns to normal.
Trap categories for this question
Scenario analysis trap
Scalability is the ability to increase capacity to handle growing demand, but it does not inherently imply automatic scaling down. Elasticity includes both scaling up and down dynamically, which is the key difference in this scenario.
Detailed technical explanation
How to think about this question
Under the hood, Azure App Service autoscale uses Azure Monitor metrics and the autoscale engine to evaluate thresholds (e.g., average CPU > 70% for 10 minutes) and then calls the Azure Resource Manager API to add or remove instances. A subtle behavior is the 'cool-down' period (default 5 minutes) that prevents flapping—rapid scaling actions that could cause instability. In a real-world marketing campaign, if autoscale rules are not properly tuned, you might experience 'scale-out lag' where new instances take 1-2 minutes to become healthy, potentially causing request throttling during sudden spikes.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
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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 — The scenario describes automatically adding and removing App Service instances in response to real-time traffic spikes, which is the definition of elasticity. Elasticity is the ability to dynamically scale resources up or down to match demand, ensuring you only pay for what you use. In Azure, this is implemented via autoscale rules that adjust the instance count based on metrics like CPU or request queue length.
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.
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
4 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 an e-commerce application on Azure. During the holiday season, the application experiences a sudden 10x increase in traffic. The company uses Azure Virtual Machine Scale Sets configured with autoscale rules based on CPU usage. The application automatically adds virtual machines during the peak and removes them when traffic subsides. Which benefit of cloud computing does this configuration primarily demonstrate?
medium- A.High availability
- ✓ B.Elasticity
- C.Fault tolerance
- D.Latency-based routing
Why B: This configuration demonstrates elasticity, which is the ability of a cloud system to automatically scale resources up or down based on demand. Azure Virtual Machine Scale Sets with autoscale rules based on CPU usage dynamically add VMs during traffic spikes and remove them when traffic subsides, directly matching resource allocation to workload requirements. This is a core benefit of cloud computing that enables cost efficiency and performance optimization without manual intervention.
Variation 2. A retail company runs an e-commerce application on Azure virtual machines. Traffic follows a predictable daily pattern: peak load occurs from 9 AM to 5 PM on weekdays. To handle this, the company configures an Azure autoscale rule that adds virtual machines at 8:30 AM and removes them at 5:30 PM each weekday. This scenario best demonstrates which cloud computing characteristic?
medium- A.High availability
- ✓ B.Elasticity
- C.Agility
- D.Fault tolerance
Why B: Elasticity is the ability to dynamically scale resources up or down to match demand. In this scenario, the autoscale rule adds VMs at 8:30 AM to handle the predictable peak load and removes them at 5:30 PM, demonstrating automatic resource provisioning and de-provisioning based on a schedule. This is a textbook example of elasticity in cloud computing.
Variation 3. A retail company runs an e-commerce application on Azure virtual machines during peak holiday seasons. The application experiences high traffic for a few weeks each year. The IT team wants to automatically provision additional compute resources during high demand and remove them when demand drops, ensuring that the company only pays for resources while they are actively in use. Which cloud computing characteristic does this approach primarily rely on?
medium- ✓ A.Elasticity
- B.Scalability
- C.High availability
- D.Fault tolerance
Why A: This approach relies on elasticity, which is the ability of a cloud system to automatically scale resources up or down based on real-time demand. In this scenario, Azure virtual machines are provisioned during peak holiday traffic and deprovisioned when demand drops, ensuring the company only pays for resources while they are actively in use. Elasticity specifically handles dynamic, short-term fluctuations, whereas scalability is a broader term for handling long-term growth.
Variation 4. A company runs an e-commerce web application on Azure virtual machines that are part of a virtual machine scale set configured with an autoscale rule based on CPU utilization. During a flash sale, customer traffic surges, causing the average CPU utilization across all instances to exceed 75% for five minutes. The scale set automatically provisions three additional VM instances to handle the increased load. After the sale ends, traffic normalizes, CPU utilization drops below 30%, and the scale set automatically removes the extra instances. This scenario best illustrates which characteristic of cloud computing?
medium- ✓ A.Elasticity
- B.High availability
- C.Fault tolerance
- D.Disaster recovery
Why A: Elasticity is the ability of a cloud system to dynamically scale resources up or down based on demand. In this scenario, the virtual machine scale set automatically adds three VM instances when CPU utilization exceeds 75% for five minutes and removes them when utilization drops below 30%, demonstrating rapid, automated scaling to match workload changes.
Last reviewed: Jun 11, 2026
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