AZ-900 Describe cloud concepts Practice Question
What does the term 'scalability' mean in the context of cloud computing?
⚠ Common exam trap
A common mix-up: candidates confuse 'scalability' with 'high availability' or 'disaster recovery'—specifically, they may pick Option A or C because they think handling failures or replicating data is part of scaling, but Azure separates these concepts: scalability is about adjusting capacity, while resilience and geo-replication are about fault tolerance and data durability.
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
✓
The ability to increase or decrease resources to match workload demand
Scalability in cloud computing refers to the ability to dynamically adjust computing resources—such as virtual machines, storage, or database throughput—up or down to match fluctuating workload demands. This is a core cloud characteristic that enables cost efficiency by paying only for what you use, and it is typically implemented through horizontal scaling (adding/removing instances) or vertical scaling (resizing an instance). In Azure, this is achieved via features like Virtual Machine Scale Sets or Azure App Service auto-scale rules.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The ability to automatically recover from failures without data loss
Why it's wrong here
This describes high availability and fault tolerance, achieved through redundant components, failover clusters, and backup/recovery processes that maintain uptime and protect data integrity. It is about resilience and business continuity, ensuring a system can resume operation or avoid downtime after a failure. Scalability does not address fault recovery; instead, it focuses on dynamically adding or removing resources to align with workload changes.
- ✓
The ability to increase or decrease resources to match workload demand
Why this is correct
This is the definition of scalability, covering both vertical scaling (changing the size of a single resource, such as CPU or memory) and horizontal scaling (adding or removing instances to distribute load). Azure implements this through capabilities like Virtual Machine Scale Sets, Azure Autoscale, and App Service scaling, allowing systems to adapt to workload variations automatically. The goal is to match resource provisioning with real-time demand to optimize performance and cost.
- ✗
The ability to replicate data across multiple geographic regions
Why it's wrong here
Replicating data across regions is a geo-redundancy and disaster recovery mechanism that ensures data durability and provides low-latency access from distributed locations. It does not alter the number of compute instances or service capacity in response to demand, which is the essence of scalability. Scalability pertains to horizontal or vertical resource scaling, not to data placement or regional replication for resilience.
- ✗
The ability to deploy applications with no downtime
Why it's wrong here
This capability refers to deployment strategies such as rolling updates or blue-green deployments that keep an application available while new versions are released. It is a release management and operational continuity concern, not a matter of adjusting computing resources to handle fluctuating load. Scalability is specifically about provisioning or deprovisioning capacity based on demand, distinct from ensuring availability during software updates.
Go deeper
Related to this question
Learn chapter
What is Cloud Computing?
Key term
Cloud computing
Cloud computing is the on-demand delivery of IT resources over the internet, allowing users to access computing power, storage, and applications without owning physical hardware.
Key term
Azure App Service
Azure App Service is a fully managed platform for building, deploying, and scaling web applications and APIs without managing the underlying infrastructure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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