- A
High availability
Why wrong: High availability refers to ensuring services remain operational despite failures. It does not directly address cost per unit, which is the focus of the question.
- B
Elasticity
Why wrong: Elasticity allows resources to scale up or down based on demand, which can reduce waste but does not explain why the cloud provider's base per-unit cost is lower than on-premises procurement.
- C
Economies of scale
Economies of scale occur when a provider's large size enables it to purchase hardware, energy, and bandwidth at much lower prices per unit. These savings are passed to customers, making cloud services cost-effective even for small deployments.
- D
Fault tolerance
Why wrong: Fault tolerance is the ability of a system to continue functioning even if components fail. It is unrelated to the cost advantage of using a large cloud provider.
Quick Answer
The answer is economies of scale, because a large cloud provider like Microsoft can spread the enormous fixed costs of building and operating data centers—including hardware, power, cooling, and staffing—across millions of customers, drastically lowering the per-unit cost for compute and storage. This means even a small business consuming only a few virtual machines benefits from the same cost efficiencies as a global enterprise, making Azure cheaper than running an on-premises server room. On the AZ-900 exam, this concept tests your understanding of how cloud pricing models differ from traditional capital expenditure; a common trap is confusing economies of scale with “elasticity” or “high availability.” Remember the mnemonic “Scale Saves” to recall that the more customers share the infrastructure, the lower each individual’s cost becomes.
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 small business runs its IT infrastructure in a small on-premises server room. The business owner is considering moving to Azure and asks the IT manager: 'How can a large cloud provider like Microsoft offer compute and storage at a lower per-unit cost than I can get by purchasing my own servers, even though I only need a few virtual machines?' Which cloud computing benefit best answers this question?
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 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
Economies of scale
Option C is correct because economies of scale allow Microsoft to spread massive capital and operational costs (data center construction, power, cooling, hardware procurement) across millions of customers. This per-unit cost reduction means even a small business consuming only a few virtual machines benefits from the same low-cost infrastructure that a large enterprise would, making Azure's compute and storage cheaper than purchasing and maintaining dedicated on-premises servers.
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 refers to ensuring services remain operational despite failures. It does not directly address cost per unit, which is the focus of the question.
- ✗
Elasticity
Why it's wrong here
Elasticity allows resources to scale up or down based on demand, which can reduce waste but does not explain why the cloud provider's base per-unit cost is lower than on-premises procurement.
- ✓
Economies of scale
Why this is correct
Economies of scale occur when a provider's large size enables it to purchase hardware, energy, and bandwidth at much lower prices per unit. These savings are passed to customers, making cloud services cost-effective even for small deployments.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Fault tolerance
Why it's wrong here
Fault tolerance is the ability of a system to continue functioning even if components fail. It is unrelated to the cost advantage of using a large cloud provider.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse economies of scale with elasticity, thinking that scaling resources up/down automatically reduces per-unit cost, when in fact elasticity only optimizes total cost by matching usage, not the underlying unit price of compute or storage.
Detailed technical explanation
How to think about this question
Under the hood, economies of scale in Azure are driven by massive procurement discounts (e.g., Microsoft buys CPUs, SSDs, and network gear at bulk rates far below retail), custom hardware design (e.g., Azure's own server blades and networking switches), and optimized power usage effectiveness (PUE) in hyper-scale data centers (often below 1.2). For example, Azure can negotiate per-GiB storage costs that are orders of magnitude lower than a small business paying retail for a single SAN array, and this saving is passed on to customers regardless of their individual consumption level.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Describe cloud concepts — study guide chapter
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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: Economies of scale — Option C is correct because economies of scale allow Microsoft to spread massive capital and operational costs (data center construction, power, cooling, hardware procurement) across millions of customers. This per-unit cost reduction means even a small business consuming only a few virtual machines benefits from the same low-cost infrastructure that a large enterprise would, making Azure's compute and storage cheaper than purchasing and maintaining dedicated on-premises servers.
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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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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