AZ-104 Deploy and Manage Azure Compute Practice Question
A public web application runs on two identical VMs behind a load balancer. The region supports availability zones. The business wants the app to keep serving traffic if one datacenter in the region becomes unavailable. What should the administrator use?
⚠ Common exam trap
Many exam-takers confuse an availability set (which protects against rack failures within a single datacenter) with availability zones (which protect against full datacenter outages), leading candidates to choose the cheaper but insufficient option A.
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
✓
Availability zones for the two VMs
Deploying the two VMs in different availability zones within the same region protects against a single datacenter failure. Each availability zone is a physically separate datacenter with independent power, cooling, and networking. If one zone goes down, the load balancer automatically routes traffic to the VM in the other zone, ensuring the application continues serving traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
An availability set with two VMs
Why it's wrong here
An availability set with two VMs distributes them across fault domains and update domains, but those domains are constrained to a single datacenter cluster within a region. This configuration protects against rack-level hardware failures and planned maintenance windows, but it cannot survive a full datacenter or availability zone outage because both VMs may live in the same zone. If that zone fails, the entire application is unavailable, so this is not the correct answer.
When this WOULD be correct
An availability set would be correct if the question asked for protection against rack-level failures (e.g., server or network switch failure) within a single datacenter, and the region did not support availability zones.
- ✓
Availability zones for the two VMs
Why this is correct
Availability zones are the right design when the business needs resiliency against a full datacenter or zone outage within a supported region. Placing the VMs in different zones keeps the application available if one zone has a failure, assuming the load balancer and application are designed accordingly.
- ✗
A single virtual machine scale set instance
Why it's wrong here
A single-instance virtual machine scale set still represents a single point of failure because there is only one VM to handle traffic. If that instance crashes, the underlying host fails, or a maintenance event forces a reboot, the application goes down. Autoscaling and orchestration features do not add resilience by themselves; a scale set must run at least two instances, ideally across availability zones or fault domains, to provide redundancy.
When this WOULD be correct
When the requirement is to automatically scale the number of VM instances based on load, and the region does not support availability zones, a scale set with multiple instances in an availability set would be correct.
- ✗
A proximity placement group
Why it's wrong here
A proximity placement group is designed to minimize network latency by co-locating VMs in the same geographic location, often within the same datacenter or availability zone. This deliberate co-location increases the risk of correlated failures, as both VMs may depend on the same power, cooling, and network infrastructure. A proximity placement group does not provide any zone or datacenter redundancy, so using it alone would fail to meet the resiliency requirement.
When this WOULD be correct
An administrator needs to minimize network latency between two VMs running a latency-sensitive application (e.g., HPC or real-time data processing) and is not concerned with datacenter failure. The question would specify low latency as the primary requirement.
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-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓Availability zones for the two VMsCorrect answer▾
Why this is correct
Availability zones are the right design when the business needs resiliency against a full datacenter or zone outage within a supported region. Placing the VMs in different zones keeps the application available if one zone has a failure, assuming the load balancer and application are designed accordingly.
✗An availability set with two VMsWrong answer — click to see why▾
Why this is wrong here
An availability set protects against hardware failures within a single datacenter, not against an entire datacenter outage. The question requires resilience if one datacenter becomes unavailable, which spans across datacenters, not within one.
★ When this WOULD be the correct answer
An availability set would be correct if the question asked for protection against rack-level failures (e.g., server or network switch failure) within a single datacenter, and the region did not support availability zones.
Why candidates choose this
Candidates may confuse availability sets with high availability across datacenters, or assume that distributing VMs across fault domains in an availability set provides datacenter-level redundancy.
✗A single virtual machine scale set instanceWrong answer — click to see why▾
Why this is wrong here
A single virtual machine scale set instance does not provide high availability across datacenters; it is a single VM, and if that VM's datacenter fails, the app goes down.
★ When this WOULD be the correct answer
When the requirement is to automatically scale the number of VM instances based on load, and the region does not support availability zones, a scale set with multiple instances in an availability set would be correct.
Why candidates choose this
Candidates may confuse scale sets with high availability, thinking that a scale set inherently provides redundancy, but a single instance offers no fault tolerance.
✗A proximity placement groupWrong answer — click to see why▾
Why this is wrong here
A proximity placement group reduces network latency between VMs but does not provide datacenter-level redundancy; if one datacenter fails, all VMs in the group could be affected.
★ When this WOULD be the correct answer
An administrator needs to minimize network latency between two VMs running a latency-sensitive application (e.g., HPC or real-time data processing) and is not concerned with datacenter failure. The question would specify low latency as the primary requirement.
Why candidates choose this
Candidates may confuse proximity placement groups with high availability features, thinking that grouping VMs together ensures they are spread across fault domains, which is incorrect.
Analysis generated from the official AZ-104blueprint 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
VM Availability Sets and Zones
Key term
Load balancer
A load balancer is a device or software that distributes incoming network traffic across multiple servers so no single server gets overwhelmed.
Key term
Region
A region is a distinct geographic location where a cloud provider operates multiple data centers that are connected by low-latency networks and provide cloud services.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-104 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-104 exam.