AZ-900 Describe cloud concepts Practice Question
A company runs a web application on an Azure virtual machine. The application experiences periodic traffic surges during promotional campaigns. To handle the increased load, the IT team manually changes the VM size from Standard_D2s_v3 to Standard_D8s_v3 before each campaign and then changes it back after the campaign ends. Which cloud computing concept does this scenario exemplify?
⚠ Common exam trap
Candidates often confuse manual scaling with elasticity, but elasticity specifically requires automatic, on-demand resource adjustment without human intervention.
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
✓
Scalability
This scenario exemplifies scalability, specifically vertical scaling (scaling up), because the IT team manually increases the VM size to handle higher demand and then reduces it afterward. Scalability is the ability to adjust resources to meet changing workload demands, which is exactly what occurs when changing from Standard_D2s_v3 to Standard_D8s_v3.
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 ability of a cloud system to automatically scale resources in and out in real time based on observed demand, often using autoscaling rules, health metrics, or queue depth. In this case, the administrator manually resizes the VM to handle traffic surges and later reduces it, which lacks the automatic, event-driven response that defines elasticity. This is planned, manual scalability rather than reactive elastic scaling.
When this WOULD be correct
A scenario where a cloud system automatically adjusts resources (e.g., adding or removing VMs) in response to real-time traffic changes, such as an auto-scaling group that spins up instances during a flash sale and terminates them afterward.
- ✓
Scalability
Why this is correct
Scalability is the ability to allocate more or fewer resources to a workload as needed. The manual resizing of the VM to handle traffic surges and the subsequent reduction is a clear example of vertical scalability.
- ✗
High availability
Why it's wrong here
High availability focuses on maximizing uptime by eliminating single points of failure through redundant components, such as multiple VMs in an availability set, load balancers, or cross-zone replication, so that a failure of one component does not cause service downtime. The scenario involves a single VM being resized vertically to accommodate load, with no redundant instances, failover capability, or fault-tolerant design. Thus, it does not address the goal of minimizing downtime during component failures.
When this WOULD be correct
A question describing a web application deployed across multiple Azure availability zones to remain operational during a regional outage would exemplify high availability.
- ✗
Disaster recovery
Why it's wrong here
Disaster recovery is a structured process for resuming operations after a major disruptive event, such as a regional outage, data corruption, or a cyberattack. It relies on techniques like backups, replication to a secondary region, and predefined RPO/RTO targets to restore service. The scenario describes routine capacity adjustments for expected traffic surges, not recovery from an unplanned incident, and resizing a VM does not invoke any recovery mechanism.
When this WOULD be correct
A question describing a company that replicates its web application to a secondary Azure region and uses Azure Site Recovery to failover during a regional outage would make disaster recovery 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.
✓ScalabilityCorrect answer▾
Why this is correct
Scalability is the ability to allocate more or fewer resources to a workload as needed. The manual resizing of the VM to handle traffic surges and the subsequent reduction is a clear example of vertical scalability.
✗ElasticityWrong answer — click to see why▾
Why this is wrong here
Elasticity refers to the ability to automatically scale resources up or down based on demand, but in this scenario, the VM size changes are performed manually, not automatically.
★ When this WOULD be the correct answer
A scenario where a cloud system automatically adjusts resources (e.g., adding or removing VMs) in response to real-time traffic changes, such as an auto-scaling group that spins up instances during a flash sale and terminates them afterward.
Why candidates choose this
Candidates often confuse elasticity with scalability because both involve handling variable workloads, but elasticity specifically implies automatic, dynamic adjustment, which is absent in this manual resizing example.
✗High availabilityWrong answer — click to see why▾
Why this is wrong here
High availability focuses on ensuring the application remains accessible despite component failures, not on adjusting resources to handle traffic surges. This scenario involves scaling resources up and down, which is scalability.
★ When this WOULD be the correct answer
A question describing a web application deployed across multiple Azure availability zones to remain operational during a regional outage would exemplify high availability.
Why candidates choose this
Candidates may confuse the ability to handle increased load (scalability) with the ability to remain available during failures (high availability), especially when the scenario involves traffic spikes.
✗Disaster recoveryWrong answer — click to see why▾
Why this is wrong here
Disaster recovery involves restoring IT infrastructure and data after a catastrophic failure, not handling periodic traffic surges by resizing a VM.
★ When this WOULD be the correct answer
A question describing a company that replicates its web application to a secondary Azure region and uses Azure Site Recovery to failover during a regional outage would make disaster recovery the correct answer.
Why candidates choose this
Candidates may confuse scaling up resources to handle load with recovering from a disaster, as both involve responding to unexpected events.
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
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 virtual machine
An Azure virtual machine is a software-based emulation of a physical computer that runs in Microsoft's cloud, allowing you to deploy and manage applications without owning the hardware.
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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.