The answer is elasticity. This is correct because elasticity is the cloud computing characteristic that automatically provisions and de-provisions compute resources in real time to match fluctuating demand, ensuring you only pay for what you use. In the given scenario, the seasonal e-commerce application requires resources to scale up during holiday spikes and scale down afterward, which is precisely what elasticity enables through auto-scaling and load balancers that react to metrics like CPU usage. On the Microsoft Azure Fundamentals AZ-900 exam, this concept often appears in questions contrasting elasticity with scalability—a common trap is confusing the two, but remember that scalability is the ability to handle growth (planned), while elasticity is the automatic, dynamic adjustment to real-time changes. A helpful memory tip: think of a rubber band—elasticity stretches and snaps back automatically, just like cloud resources responding to demand.
AZ-900 Describe cloud concepts Practice Question
This AZ-900 practice question tests your understanding of describe cloud concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 seasonal e-commerce application. During the holiday season, demand spikes significantly, but the company does not want to pay for idle resources the rest of the year. They want the cloud to automatically add or remove compute resources based on real-time demand. Which cloud computing characteristic does this scenario best describe?
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.
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 cloud characteristic that enables automatic scaling of resources up or down in real-time to match demand. In this scenario, the e-commerce application needs to add compute resources during holiday spikes and remove them when demand drops, avoiding paying for idle resources. This aligns directly with elasticity, which is often implemented via auto-scaling groups and load balancers that adjust capacity based on metrics like CPU utilization or request count.
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.
✗
Scalability
Why it's wrong here
Scalability is the ability to increase capacity, but it may be manual. Elasticity specifically implies automatic scaling on demand.
✓
Elasticity
Why this is correct
Elasticity allows the system to automatically provision and deprovision resources to match demand, optimizing cost and performance.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
High availability
Why it's wrong here
High availability focuses on minimizing downtime, not automatically adjusting capacity based on demand.
✗
Disaster recovery
Why it's wrong here
Disaster recovery is about recovering from failures, not about scaling to meet demand changes.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse scalability with elasticity, but scalability is a broader capability that can be manual or planned, while elasticity specifically implies automatic, bidirectional scaling in response to real-time demand.
Detailed technical explanation
How to think about this question
Under the hood, elasticity in Azure is commonly achieved through Virtual Machine Scale Sets (VMSS) with autoscale rules that use metrics like average CPU percentage or queue depth to trigger scale-out and scale-in operations. A subtle behavior is the 'cool-down' period (default 5 minutes) that prevents flapping—rapid scaling actions caused by transient metric spikes. In a real-world scenario, a flash sale might cause a sudden surge; elasticity ensures new VMs are provisioned within minutes, but the autoscale engine must be configured with appropriate thresholds to avoid over-provisioning.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
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 cloud characteristic that enables automatic scaling of resources up or down in real-time to match demand. In this scenario, the e-commerce application needs to add compute resources during holiday spikes and remove them when demand drops, avoiding paying for idle resources. This aligns directly with elasticity, which is often implemented via auto-scaling groups and load balancers that adjust capacity based on metrics like CPU utilization or request count.
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". 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.
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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 company runs a seasonal e-commerce application. During holidays, traffic increases tenfold, but the company does not want to over-provision resources for the rest of the year. They want to add or remove server capacity automatically based on real-time demand and pay only for what they use. Which cloud computing characteristic does this scenario describe?
easy
A.High availability
✓ B.Elasticity
C.Reliability
D.Fault tolerance
Why B: Elasticity is the cloud computing characteristic that enables automatic scaling of resources up or down based on real-time demand. In this scenario, the e-commerce application needs to handle a tenfold traffic increase during holidays without over-provisioning for the rest of the year, which is exactly what elasticity provides by adding or removing server capacity dynamically and charging only for what is used.
Variation 2. A company runs a web application that experiences sudden spikes in traffic during promotional events. They want to automatically add more virtual machines during high demand and remove them when traffic subsides, paying only for the resources used. Which cloud computing benefit does this scenario describe?
medium
✓ A.Elasticity
B.Scalability
C.High availability
D.Fault tolerance
Why A: This scenario describes elasticity, which is the ability of a cloud system to automatically provision and de-provision resources (such as virtual machines) in response to real-time demand changes. The key phrase 'automatically add more virtual machines during high demand and remove them when traffic subsides, paying only for the resources used' directly matches the cloud computing benefit of elasticity, where scaling is dynamic and resource usage is metered, ensuring cost efficiency.
Variation 3. A company runs a web application that experiences unpredictable traffic spikes. They want the cloud to automatically increase the number of virtual machine instances during high demand and decrease them when demand drops, without manual intervention. Which cloud computing characteristic does this describe?
easy
✓ A.Elasticity
B.Scalability
C.High availability
D.Fault tolerance
Why A: Elasticity is the ability of a cloud system to dynamically scale resources up and down based on real-time demand. Scalability refers to the ability to handle growth but may not be automatic. High availability focuses on uptime, and fault tolerance ensures operation during failures. This scenario specifically describes automatic scaling, which is elasticity.
Variation 4. A startup wants to deploy a web application that experiences unpredictable traffic spikes. They need to scale resources automatically without manual intervention. Which benefit of cloud computing directly addresses this requirement?
easy
A.High availability
✓ B.Elasticity
C.Disaster recovery
D.Fault tolerance
Why B: Elasticity is the cloud computing benefit that enables resources to automatically scale out (add instances) during traffic spikes and scale in (remove instances) when demand drops, without manual intervention. This directly matches the startup's need to handle unpredictable traffic patterns by dynamically adjusting compute capacity, typically using services like Azure Virtual Machine Scale Sets or Azure App Service auto-scale rules.
Last reviewed: Jun 11, 2026
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