The answer is Azure Virtual Machine Scale Sets configured across Availability Zones. This is correct because VMSS can deploy identical VM instances into multiple zones within an Azure region, ensuring that if one zone fails, the other zones continue running your application. When you attach an Azure Load Balancer or Application Gateway to the scale set, traffic is automatically distributed across all healthy instances, providing both high availability and load balancing in a single service. On the AZ-900 exam, this scenario tests your understanding of how Azure’s compute and networking services work together for resilience; a common trap is confusing a single-region scale set with one that spans zones, or thinking a regular availability set provides the same cross-zone distribution. Remember the memory tip: “Scale sets span zones, load balancers share the load” — if the question mentions identical VMs across multiple zones with automatic traffic distribution, the answer is always VMSS with Availability Zones.
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which Azure compute service runs identical VM instances in multiple Availability Zones with automatic load balancing?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Virtual Machine Scale Sets across Availability Zones
Azure Virtual Machine Scale Sets (VMSS) can be configured to span multiple Availability Zones, automatically distributing VM instances across those zones for high availability. When combined with an Azure Load Balancer or Application Gateway, the scale set provides automatic load balancing of incoming traffic across all instances, meeting the requirement exactly.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Azure Availability Sets
Why it's wrong here
Availability Sets work within a single datacenter; Scale Sets can span Availability Zones.
✓
Azure Virtual Machine Scale Sets across Availability Zones
Why this is correct
VMSS deployed across AZs provides zone-redundant auto-scaling VM groups with cross-zone load balancing.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Dedicated Host
Why it's wrong here
Dedicated Host provides physical isolation; it doesn't provide auto-scaling across zones.
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Availability Sets (which only protect within a single datacenter) with Availability Zones (which protect across datacenters), leading them to select Option A even though it lacks both multi-zone distribution and automatic load balancing.
Detailed technical explanation
How to think about this question
Under the hood, a VMSS configured across Availability Zones uses a zone-balancing algorithm to distribute new instances evenly across the selected zones, and the associated load balancer uses a hash-based distribution (e.g., 5-tuple hash for Azure Load Balancer) to route traffic. A real-world scenario is a web front-end that must survive an entire zone outage; the scale set automatically replaces failed instances in the remaining zones, and the load balancer continues to direct traffic only to healthy instances.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Virtual Machine Scale Sets across Availability Zones — Azure Virtual Machine Scale Sets (VMSS) can be configured to span multiple Availability Zones, automatically distributing VM instances across those zones for high availability. When combined with an Azure Load Balancer or Application Gateway, the scale set provides automatic load balancing of incoming traffic across all instances, meeting the requirement exactly.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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