AZ-900 Describe cloud concepts Practice Question
A company runs a critical line-of-business application on a single on-premises server. The company is migrating the application to Azure and wants to minimize downtime if the server hardware fails. The architect proposes deploying the application on two Azure virtual machines (VMs) in the same region, placed in an availability set. This configuration is designed to ensure that if one VM fails due to hardware failure or planned maintenance, the other VM remains running and the application stays available. Which cloud computing concept does this configuration primarily illustrate?
⚠ Common exam trap
Watch out — candidates often confuse high availability with fault tolerance, but Azure availability sets provide HA (minimizing downtime) not fault tolerance (zero downtime), and the question's wording about 'minimizing downtime' explicitly points to HA.
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
✓
High availability
High availability (HA) is the correct concept because the configuration uses two VMs in an availability set to ensure the application remains accessible despite hardware failures or planned maintenance. An availability set distributes VMs across fault domains and update domains, guaranteeing that at least one VM stays operational during Azure platform events. This directly aligns with HA's goal of minimizing downtime and maximizing uptime for critical workloads.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Fault tolerance
Why it's wrong here
Fault tolerance means a system can continue operating without any interruption when a component fails. Two VMs in an availability set do not provide instantaneous failover; there will be a brief pause while the application fails over to the second VM, and the second VM might be rebooted during planned maintenance. Therefore, this configuration offers high availability, not fault tolerance.
When this WOULD be correct
A question describing a system that continues operating without interruption despite a hardware failure, such as using multiple VMs in an availability zone with load balancing and automatic failover that ensures no downtime and no data loss.
- ✓
High availability
Why this is correct
High availability minimizes downtime by using redundant components so that if one fails, another takes over with minimal interruption. An availability set ensures that VMs are placed on different physical hardware and updated during different maintenance windows, so at least one VM remains running. This matches the goal of keeping the application available despite a single server failure, which is the definition of high availability.
- ✗
Disaster recovery
Why it's wrong here
Disaster recovery involves restoring operations after a catastrophic failure that affects an entire region or data center, such as a natural disaster. The scenario describes a single server failure within one region, not a region-wide outage. Disaster recovery would require replication across regions, which is not part of the described configuration.
When this WOULD be correct
A company runs a critical application on-premises and wants to protect against a regional outage (e.g., natural disaster). The architect deploys the application on Azure VMs in two different regions with Azure Site Recovery configured to replicate and fail over to the secondary region. This configuration primarily illustrates disaster recovery.
- ✗
Elasticity
Why it's wrong here
Elasticity is the ability to dynamically add or remove compute resources to match changing demand, such as scaling out VMs during peak traffic and scaling in when demand drops. The scenario describes a single server failure within an availability set, where the goal is to keep the application running through redundancy—not to adjust capacity based on workload fluctuations. An availability set does not auto-scale; it only places VMs on separate fault and update domains, which is unrelated to elasticity.
When this WOULD be correct
A question describing an application that experiences variable traffic loads, such as an e-commerce site with seasonal spikes, and requires automatic addition or removal of VMs to handle demand changes, would make elasticity 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.
✓High availabilityCorrect answer▾
Why this is correct
High availability minimizes downtime by using redundant components so that if one fails, another takes over with minimal interruption. An availability set ensures that VMs are placed on different physical hardware and updated during different maintenance windows, so at least one VM remains running. This matches the goal of keeping the application available despite a single server failure, which is the definition of high availability.
✗Fault toleranceWrong answer — click to see why▾
Why this is wrong here
Fault tolerance implies zero downtime and no data loss even if a component fails, but an availability set with two VMs still has a single point of failure at the application layer and does not guarantee instant failover without data loss.
★ When this WOULD be the correct answer
A question describing a system that continues operating without interruption despite a hardware failure, such as using multiple VMs in an availability zone with load balancing and automatic failover that ensures no downtime and no data loss.
Why candidates choose this
Candidates confuse high availability with fault tolerance because both involve redundancy; they may think that having two VMs in an availability set provides fault tolerance, but it only ensures availability, not zero downtime.
✗Disaster recoveryWrong answer — click to see why▾
Why this is wrong here
Disaster recovery (DR) involves recovering from a major outage by failing over to a secondary site or region, not by maintaining continuous operation within the same region. The scenario describes local hardware failure within a single region, which is addressed by high availability, not DR.
★ When this WOULD be the correct answer
A company runs a critical application on-premises and wants to protect against a regional outage (e.g., natural disaster). The architect deploys the application on Azure VMs in two different regions with Azure Site Recovery configured to replicate and fail over to the secondary region. This configuration primarily illustrates disaster recovery.
Why candidates choose this
Candidates may confuse high availability (keeping services running despite local failures) with disaster recovery (recovering from catastrophic events), especially when the scenario mentions 'hardware failure' and 'minimize downtime' without specifying the scope of the failure.
✗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, not to maintaining application uptime during hardware failures. The scenario focuses on minimizing downtime from hardware failure, not on scaling.
★ When this WOULD be the correct answer
A question describing an application that experiences variable traffic loads, such as an e-commerce site with seasonal spikes, and requires automatic addition or removal of VMs to handle demand changes, would make elasticity the correct answer.
Why candidates choose this
Candidates may confuse elasticity with high availability because both involve multiple VMs, but elasticity is about scaling to meet demand, not about ensuring continuous operation during failures.
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
Availability set
An Availability set is a cloud computing feature that groups virtual machines across multiple fault domains and update domains to ensure high availability during hardware failures or planned maintenance.
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.
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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.