- A
High availability
Why wrong: High availability ensures that services remain operational with minimal downtime, usually through redundancy. It does not specifically address dynamic scaling of capacity based on demand.
- B
Elasticity
Elasticity is the ability to automatically scale resources up or out (and down or in) according to workload demand, thereby aligning cost with usage. This is exactly what the scenario describes.
- C
Reliability
Why wrong: Reliability is the ability of a system to recover from failures and continue to function. It is not primarily about scaling to meet changing demand.
- D
Fault tolerance
Why wrong: Fault tolerance enables a system to continue operating even when components fail. It does not address scaling resources based on 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 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?
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 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.
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
High availability ensures that services remain operational with minimal downtime, usually through redundancy. It does not specifically address dynamic scaling of capacity based on demand.
- ✓
Elasticity
Why this is correct
Elasticity is the ability to automatically scale resources up or out (and down or in) according to workload demand, thereby aligning cost with usage. This is exactly what the scenario describes.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Reliability
Why it's wrong here
Reliability is the ability of a system to recover from failures and continue to function. It is not primarily about scaling to meet changing demand.
- ✗
Fault tolerance
Why it's wrong here
Fault tolerance enables a system to continue operating even when components fail. It does not address scaling resources based on demand.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse elasticity with high availability, thinking that adding more servers automatically ensures uptime, but high availability focuses on fault tolerance and redundancy, not dynamic scaling based on demand.
Detailed technical explanation
How to think about this question
Under the hood, elasticity is implemented via auto-scaling groups and load balancers that monitor metrics such as CPU utilization or request count against defined thresholds (e.g., 70% CPU triggers scale-out). In Azure, this is achieved through Virtual Machine Scale Sets (VMSS) or Azure App Service auto-scale rules, which can add or remove instances within minutes, and billing is metered per second for compute resources. A subtle behavior is that scale-in operations often have a cooldown period (e.g., 5–10 minutes) to avoid flapping, which can impact applications with sudden traffic 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 — 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.
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.
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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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