AZ-900 Describe cloud concepts Practice Question
A company uses a public cloud service where they share physical hardware with other customers. This allows the provider to offer low prices due to economies of scale. Which cloud characteristic is being described?
⚠ Common exam trap
It's easy for candidates to confuse multi-tenancy with elasticity or scalability, because both involve resource management, but the key differentiator is the sharing of physical hardware with other customers for cost efficiency.
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
✓
Multi-tenancy
Multi-tenancy is the cloud characteristic where a single instance of physical hardware (or software) serves multiple customers (tenants), isolating their data and configurations while sharing underlying resources. This sharing enables the provider to achieve economies of scale, reducing per-customer costs and allowing low prices. The scenario explicitly describes sharing physical hardware with other customers, which is the core definition of multi-tenancy.
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 it's wrong here
Elasticity is the automatic ability of a cloud service to scale its allocated resources up or down in response to current demand, often using performance metrics or schedules. It is a dynamic capacity management feature that helps match cost to usage, but it says nothing about who else is using the same physical hardware. A service can be highly elastic even if it runs on a dedicated, single-tenant infrastructure. Thus elasticity is unrelated to the multi-tenant resource pooling described in the question.
When this WOULD be correct
Elasticity would be correct in a question like: 'A company’s web application experiences sudden spikes in traffic. The cloud service automatically adds virtual machines during peak times and removes them when demand drops. Which cloud characteristic is this?'
- ✗
Scalability
Why it's wrong here
Scalability is the capability of a system to handle increasing loads by adding more resources, either by scaling up (more power to an existing instance) or scaling out (adding more instances). It solves the problem of growth and performance, but it does not imply that those resources are shared with other independent customers. A workload can be highly scalable while running on completely dedicated physical servers in a private data center. Scalability therefore does not describe the cost-sharing model of shared physical infrastructure.
When this WOULD be correct
A question asking: 'A company expects a sudden spike in traffic and needs to automatically add more virtual machines to handle the load. Which cloud characteristic is this?' would make scalability the correct answer.
- ✓
Multi-tenancy
Why this is correct
Multi-tenancy is the defining model of public cloud whereby a provider pools physical compute, storage, and networking hardware and serves many customers from that shared infrastructure. Logical isolation is enforced through hypervisors and software-defined networking, so each tenant's data and workloads remain private even though they reside on the same physical host. This sharing drives economies of scale, allowing the provider to offer pay-as-you-go pricing while maintaining security boundaries. Multi-tenancy is precisely the concept described in the question stem.
- ✗
High availability
Why it's wrong here
High availability is a resilience design goal that focuses on keeping applications operational despite component failures, typically through redundancy, failover, and load balancing. It addresses uptime and continuity rather than how multiple customers share physical resources. Even a single-tenant private cloud can be highly available if it uses redundant hardware and automated recovery. Therefore, high availability does not explain the sharing of physical infrastructure among multiple public cloud customers.
When this WOULD be correct
A question stating: 'A company deploys their application across multiple availability zones to ensure it remains accessible even if one datacenter fails. Which cloud characteristic is this?' would make high availability the correct answer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Multi-tenancyCorrect answer▾
Why this is correct
Multi-tenancy is the defining model of public cloud whereby a provider pools physical compute, storage, and networking hardware and serves many customers from that shared infrastructure. Logical isolation is enforced through hypervisors and software-defined networking, so each tenant's data and workloads remain private even though they reside on the same physical host. This sharing drives economies of scale, allowing the provider to offer pay-as-you-go pricing while maintaining security boundaries. Multi-tenancy is precisely the concept described in the question stem.
✗ElasticityWrong answer — click to see why▾
Why this is wrong here
The question describes sharing physical hardware with other customers to achieve low prices via economies of scale, which is the definition of multi-tenancy, not elasticity. Elasticity refers to automatically provisioning and de-provisioning resources to match demand.
★ When this WOULD be the correct answer
Elasticity would be correct in a question like: 'A company’s web application experiences sudden spikes in traffic. The cloud service automatically adds virtual machines during peak times and removes them when demand drops. Which cloud characteristic is this?'
Why candidates choose this
Candidates may confuse elasticity with multi-tenancy because both involve resource sharing and cost efficiency, but elasticity focuses on dynamic scaling, not shared infrastructure.
✗ScalabilityWrong answer — click to see why▾
Why this is wrong here
Scalability refers to the ability to increase or decrease resources as needed, not to sharing physical hardware with other customers. The question describes multi-tenancy, where multiple customers share the same physical infrastructure to achieve cost savings.
★ When this WOULD be the correct answer
A question asking: 'A company expects a sudden spike in traffic and needs to automatically add more virtual machines to handle the load. Which cloud characteristic is this?' would make scalability the correct answer.
Why candidates choose this
Candidates may confuse scalability with multi-tenancy because both involve resource optimization, but scalability focuses on adjusting resources to meet demand, not on sharing infrastructure among multiple tenants.
✗High availabilityWrong answer — click to see why▾
Why this is wrong here
High availability refers to systems remaining operational despite failures, not to sharing physical hardware among customers. The question describes multi-tenancy, where multiple customers share infrastructure to achieve cost savings.
★ When this WOULD be the correct answer
A question stating: 'A company deploys their application across multiple availability zones to ensure it remains accessible even if one datacenter fails. Which cloud characteristic is this?' would make high availability the correct answer.
Why candidates choose this
Candidates may confuse high availability with the general reliability of public cloud services, or think that sharing hardware implies redundancy, but high availability focuses on uptime, not resource sharing.
Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
What is Cloud Computing?
Key term
Public cloud
A public cloud is a computing model where third-party providers deliver IT resources like servers, storage, and applications over the internet to multiple customers on a pay-as-you-go basis.
Key term
Economies of scale
Economies of scale is the cost advantage that businesses get when production becomes more efficient as they grow larger, reducing the cost per unit.
About these practice questions
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.