AZ-900 Describe cloud concepts Practice Question
A company runs a web application on two VMs in the same Availability Set. What is the guaranteed SLA for the VMs?
⚠ Common exam trap
Many exam-takers confuse the 99.9% single-VM SLA with the 99.95% multi-VM Availability Set SLA, or mistakenly think Availability Zones (99.99%) are the same as Availability Sets.
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
✓
99.95%
Microsoft guarantees a 99.95% SLA for two or more virtual machines deployed in the same Availability Set because the set distributes VMs across separate fault domains and update domains, ensuring that at least one VM remains available during planned maintenance or hardware failures. The SLA applies only when all VMs are in the same Availability Set and all disks are managed disks, as per the Azure Compute SLA terms.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
99.9%
Why it's wrong here
The 99.9% SLA is associated with a single VM that has no availability option, provided all operating system and data disks use Premium SSD or Ultra Disk storage. This figure does not reflect the higher reliability achieved by an Availability Set, which raises the guaranteed uptime to 99.95% when two or more VMs are grouped together. Since the scenario involves an Availability Set, 99.9% underestimates the actual guaranteed uptime and is incorrect.
- ✓
99.95%
Why this is correct
When two or more VMs are placed in the same Availability Set, Azure guarantees that you will have connectivity to at least one instance at least 99.95% of the time. The Availability Set spreads VMs across fault domains (racks with independent power and networking) and update domains (groups rebooted sequentially during maintenance), reducing the risk of concurrent downtime. This redundancy level specifically yields the 99.95% SLA, making it the correct answer for the stated scenario.
- ✗
99.99%
Why it's wrong here
The 99.99% monthly uptime SLA applies only when two or more virtual machines are deployed across two or more Availability Zones, which provides datacenter-level fault isolation. An Availability Set alone—distributing VMs within a single datacenter across fault and update domains—guarantees a maximum of 99.95%, not 99.99%. Therefore, selecting 99.99% for an Availability Set deployment is incorrect because it requires a higher redundancy tier.
- ✗
100%
Why it's wrong here
No Azure service, including Virtual Machines, offers a 100% uptime SLA because unexpected hardware failures, network issues, datacenter-level incidents, and planned maintenance can all cause downtime. Azure SLAs are financial-backed guarantees expressed as a percentage of monthly uptime, and if the SLA is not met, customers may receive service credits. A 100% guarantee is commercially and practically unattainable, making this option incorrect.
Go deeper
Related to this question
Learn chapter
High Availability and Scalability
Key term
Availability
Availability is the measure of how often a system or service is operational and accessible when needed, typically expressed as a percentage of uptime.
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.
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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.