AZ-900 Describe cloud concepts Practice Question
A company wants to ensure their application remains available even if an entire Azure region experiences an outage. Which Azure feature should they implement?
⚠ Common exam trap
A common mix-up: candidates confuse Availability zones (which protect against datacenter failures within a region) with Region pairs (which protect against full region outages), and they often overlook that Availability zones cannot survive a complete region failure because they share the same regional boundary.
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
✓
Region pairs
Region pairs are designed to provide resilience against a complete Azure region outage by pairing each region with another region in the same geography (e.g., East US paired with West US). If one region fails, Azure can fail over services like storage (GRS) and SQL Database (Geo-Replication) to the paired region, ensuring application availability. This is the only option that protects against an entire region failure, as it leverages physically separate datacenters with independent power, cooling, and networking.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Availability sets
Why it's wrong here
Availability sets are logical groupings of VMs that ensure those VMs are placed on different fault domains (distinct racks with independent power and network) and update domains (groups that can be rebooted together during planned maintenance). This protects against hardware failures and planned maintenance within a single datacenter, but it is confined to that one datacenter. They cannot help with a full regional outage because availability sets have no mechanism to replicate data or failover to another geographic location.
When this WOULD be correct
A question asking how to ensure high availability for VMs within a single region by distributing them across multiple fault and update domains would make availability sets the correct answer.
- ✗
Availability zones
Why it's wrong here
Availability zones are physically separate datacenters within the same Azure region, each with its own independent power, cooling, and networking. They protect against datacenter-level failures, such as a fire or cooling loss, because your resources can be distributed across zones. However, all zones are still inside the same regional boundary, so an event that takes down the entire region—like a catastrophic natural disaster—would also take down all zones, meaning they do not provide cross-region fault tolerance.
When this WOULD be correct
A question that asks for protecting an application from a single datacenter failure within a region, such as: 'A company wants to ensure high availability for a virtual machine in case of a datacenter failure within an Azure region. Which feature should they use?'
- ✓
Region pairs
Why this is correct
Region pairs are Azure's built-in disaster recovery mechanism: each region is paired with another region in the same geography, often at least 300 miles away, to ensure data residency and continuity. Microsoft prioritizes one region in the pair during an outage, and Azure services like Storage and SQL DB automatically fail over to the paired region. This cross-region replication is designed specifically to keep applications available even when an entire region goes down, making it the correct answer.
- ✗
Load balancer
Why it's wrong here
A load balancer distributes incoming network traffic across multiple backend instances, such as VMs or virtual machine scale sets, but it operates within a single region and a single virtual network. It can detect and route around unhealthy instances, but it has no concept of cross-region failover or coordinated replication between geographic regions. If the entire region hosting that load balancer becomes unavailable, the load balancer itself fails, so it cannot ensure application availability across a regional outage.
When this WOULD be correct
A question asking how to distribute incoming traffic across multiple virtual machines in the same region for high availability and scalability would make a load balancer 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.
✓Region pairsCorrect answer▾
Why this is correct
Region pairs are Azure's built-in disaster recovery mechanism: each region is paired with another region in the same geography, often at least 300 miles away, to ensure data residency and continuity. Microsoft prioritizes one region in the pair during an outage, and Azure services like Storage and SQL DB automatically fail over to the paired region. This cross-region replication is designed specifically to keep applications available even when an entire region goes down, making it the correct answer.
✗Availability setsWrong answer — click to see why▾
Why this is wrong here
Availability sets protect against failures within a single Azure datacenter (e.g., rack or update domain failures), not against an entire region outage.
★ When this WOULD be the correct answer
A question asking how to ensure high availability for VMs within a single region by distributing them across multiple fault and update domains would make availability sets the correct answer.
Why candidates choose this
Candidates often confuse availability sets with region-level redundancy, assuming 'sets' implies geographic distribution, but they only operate within one region.
✗Availability zonesWrong answer — click to see why▾
Why this is wrong here
Availability zones protect against datacenter-level failures within a single region, not against an entire region outage.
★ When this WOULD be the correct answer
A question that asks for protecting an application from a single datacenter failure within a region, such as: 'A company wants to ensure high availability for a virtual machine in case of a datacenter failure within an Azure region. Which feature should they use?'
Why candidates choose this
Candidates confuse 'zone' with 'region' and think that availability zones span multiple regions, or they assume that zones provide region-level redundancy.
✗Load balancerWrong answer — click to see why▾
Why this is wrong here
A load balancer distributes traffic within a region but does not provide cross-region failover; it cannot maintain availability if an entire Azure region fails.
★ When this WOULD be the correct answer
A question asking how to distribute incoming traffic across multiple virtual machines in the same region for high availability and scalability would make a load balancer the correct answer.
Why candidates choose this
Candidates may think a load balancer ensures availability across regions, confusing its regional distribution with cross-region disaster recovery.
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
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
Feature
A feature is a distinct unit of functionality that delivers value to the user, often managed and tracked throughout the software development lifecycle.
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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.