AZ-900 Describe cloud concepts Practice Question
A startup application experiences unpredictable traffic spikes. The application runs on Azure Virtual Machines. They want the VMs to automatically increase in number during peak times and decrease during low usage, without manual intervention. Which cloud characteristic does this requirement describe?
⚠ Common exam trap
Candidates often confuse elasticity (dynamic scaling) with high availability (fault tolerance), because both involve multiple VMs, but elasticity is specifically about adjusting capacity to demand, not about maintaining uptime during failures.
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 characteristic that enables resources to automatically scale out (increase) during high demand and scale in (decrease) during low demand, matching capacity to workload in real time. In this scenario, Azure Virtual Machines can be configured with autoscale rules (e.g., based on CPU > 75% for 5 minutes) to add or remove VM instances without manual intervention. This directly addresses the startup's need to handle unpredictable traffic spikes while optimizing cost.
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 this is correct
Elasticity is a cloud characteristic that dynamically provisions and releases resources to match the current workload. For a startup with unpredictable traffic spikes, elasticity ensures capacity scales out during surges and scales in during lulls, minimizing cost and performance bottlenecks. This is achieved through autoscaling policies that monitor metrics like CPU or request count.
- ✗
High availability
Why it's wrong here
High availability (HA) ensures that applications remain accessible despite component failures by using redundant instances, load balancers, and fault-tolerant architectures. HA is about maintaining uptime and eliminating single points of failure, not about adding or removing resources in response to load changes. Even if an HA system is always on, it does not automatically expand capacity during a traffic spike unless combined with elastic scaling.
When this WOULD be correct
A question asks: 'A company requires its application to remain operational even if one Azure region experiences an outage. Which cloud characteristic is most important?' In that context, high availability would be correct.
- ✗
Disaster recovery
Why it's wrong here
Disaster recovery (DR) involves predefined processes and infrastructure to restore IT systems and data after a catastrophic event, such as regional outages or data corruption. It does not address varying traffic demand; DR focuses on RTO/RPO and failover to a secondary site, not on adjusting capacity to handle spikes. While DR may include redundant resources, its purpose is business continuity, not dynamic scaling.
When this WOULD be correct
A company needs to ensure that its critical application can be quickly restored in a different Azure region after a major outage. The question would ask about the ability to recover from a disaster with minimal downtime and data loss.
- ✗
Geo-redundancy
Why it's wrong here
Geo-redundancy copies data asynchronously or synchronously to Azure paired regions to protect against region-wide disasters. This replication ensures durability and availability of data but does not dynamically adjust compute or storage capacity based on traffic. While geo-redundancy can support read scaling via read replicas in some services, it is fundamentally a data protection feature, not an elasticity mechanism.
When this WOULD be correct
A question asking for a solution that ensures data is replicated across multiple Azure regions to survive a regional outage, e.g., 'Which feature replicates storage to a secondary region hundreds of miles away?'
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.
✓ElasticityCorrect answer▾
Why this is correct
Elasticity is a cloud characteristic that dynamically provisions and releases resources to match the current workload. For a startup with unpredictable traffic spikes, elasticity ensures capacity scales out during surges and scales in during lulls, minimizing cost and performance bottlenecks. This is achieved through autoscaling policies that monitor metrics like CPU or request count.
✗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 automatically scaling resources up or down in response to traffic changes.
★ When this WOULD be the correct answer
A question asks: 'A company requires its application to remain operational even if one Azure region experiences an outage. Which cloud characteristic is most important?' In that context, high availability would be correct.
Why candidates choose this
Candidates may confuse the ability to handle increased load (elasticity) with the ability to remain operational (high availability), especially when the scenario involves unpredictable traffic spikes that could cause outages if not scaled.
✗Disaster recoveryWrong answer — click to see why▾
Why this is wrong here
Disaster recovery focuses on restoring systems and data after a catastrophic failure, not on automatically scaling resources in response to traffic spikes.
★ When this WOULD be the correct answer
A company needs to ensure that its critical application can be quickly restored in a different Azure region after a major outage. The question would ask about the ability to recover from a disaster with minimal downtime and data loss.
Why candidates choose this
Candidates may confuse disaster recovery with elasticity because both involve handling unexpected events, but disaster recovery is about recovery after failure, not scaling to meet demand.
✗Geo-redundancyWrong answer — click to see why▾
Why this is wrong here
Geo-redundancy replicates data or resources across geographically separate regions to protect against regional failures, not to automatically scale VMs based on traffic spikes.
★ When this WOULD be the correct answer
A question asking for a solution that ensures data is replicated across multiple Azure regions to survive a regional outage, e.g., 'Which feature replicates storage to a secondary region hundreds of miles away?'
Why candidates choose this
Candidates may confuse geo-redundancy with the ability to handle increased load by distributing traffic across regions, but it does not provide automatic scaling.
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
Elasticity
Elasticity is the ability of a cloud system to automatically add or remove computing resources (like servers, storage, or bandwidth) in response to real-time changes in demand.
Key term
Workload
A workload is any discrete application, service, or function that runs on a computing resource, consuming CPU, memory, storage, or network capacity.
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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.