AZ-104 Deploy and Manage Azure Compute Practice Question
A line-of-business app requires protection against a datacenter outage in a region that supports zones. You want the strongest placement resilience available for the VMs. What should you choose?
⚠ Common exam trap
Watch out — candidates often confuse availability sets (which protect against rack-level failures) with availability zones (which protect against full datacenter outages), leading them to choose the weaker option when the question explicitly demands the strongest placement resilience.
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 zone
Availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Deploying VMs across zones provides the strongest resilience against a datacenter outage because if one zone fails, the other zones remain operational. This is the highest level of protection available within a single region for IaaS VMs.
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 set
Why it's wrong here
An availability set protects workloads against failures within a single Azure datacenter by distributing VMs across fault domains (separate racks with independent power and network) and update domains (groups that reboot together during maintenance). However, all VMs in an availability set reside in the same datacenter, so it cannot protect against a complete datacenter outage. For datacenter-level resilience, you must use availability zones, which place resources in physically separate buildings within the region.
When this WOULD be correct
If the question asked for protection against hardware failures or maintenance within a single datacenter (e.g., 'You need high availability for VMs in a single region without zone support'), an availability set would be the correct answer.
- ✓
Availability zone
Why this is correct
Availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Deploying the application's VMs across multiple zones, or using zone-redundant services (such as Azure Load Balancer or Azure SQL Database), isolates the workload from a single datacenter failure. This is the correct answer because an availability zone is the only option here that explicitly spans datacenter boundaries while remaining in the same region, enabling continued operation if one zone goes down.
- ✗
Virtual machine scale set
Why it's wrong here
A virtual machine scale set is a deployment and scaling mechanism that lets you run a group of identical VMs and automatically scale in or out based on demand. While a scale set can be configured to distribute VMs across availability zones or availability sets, the scale set itself is not a resilience boundary — it does not inherently place resources in separate datacenters. Its primary purpose is operational agility and elastic capacity, not fault isolation against a datacenter outage, so it fails to meet the requirement on its own.
When this WOULD be correct
A question asks for a solution to automatically scale the number of VM instances based on demand, while maintaining high availability within a single region. The correct answer would be Virtual machine scale set with a minimum instance count spread across fault domains.
- ✗
Resource lock
Why it's wrong here
A resource lock is an Azure management control that prevents accidental deletion or modification of a resource by setting a read-only or delete lock at the subscription, resource group, or resource level. It operates entirely in the Azure control plane and has no effect on runtime availability or the physical health of a datacenter. In fact, if a datacenter fails, the locked resource remains just as unavailable as an unlocked one, so a lock offers no protection for this requirement.
When this WOULD be correct
In a scenario where you need to protect critical resources (e.g., a storage account or a virtual network) from accidental deletion or modification by users, a resource lock (CanNotDelete or ReadOnly) would be 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-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓Availability zoneCorrect answer▾
Why this is correct
Availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Deploying the application's VMs across multiple zones, or using zone-redundant services (such as Azure Load Balancer or Azure SQL Database), isolates the workload from a single datacenter failure. This is the correct answer because an availability zone is the only option here that explicitly spans datacenter boundaries while remaining in the same region, enabling continued operation if one zone goes down.
✗Availability setWrong answer — click to see why▾
Why this is wrong here
An availability set protects against failures within a single datacenter (rack/update domain failures), not against a full datacenter outage across zones. The question requires resilience across zones, which availability sets do not provide.
★ When this WOULD be the correct answer
If the question asked for protection against hardware failures or maintenance within a single datacenter (e.g., 'You need high availability for VMs in a single region without zone support'), an availability set would be the correct answer.
Why candidates choose this
Candidates often confuse availability sets with zone-level resilience, thinking 'set' implies broader protection, or they may not fully understand that availability sets only span fault domains within one datacenter.
✗Virtual machine scale setWrong answer — click to see why▾
Why this is wrong here
Virtual machine scale sets provide scaling and load balancing, not the strongest placement resilience against a datacenter outage. They distribute VMs across fault domains within a region but do not isolate across zones, so a single zone failure can affect all VMs.
★ When this WOULD be the correct answer
A question asks for a solution to automatically scale the number of VM instances based on demand, while maintaining high availability within a single region. The correct answer would be Virtual machine scale set with a minimum instance count spread across fault domains.
Why candidates choose this
Candidates may confuse scale sets' fault domain distribution with zone-level resilience, or think that the 'set' implies grouping for availability, but scale sets prioritize scaling over isolation from zone failures.
✗Resource lockWrong answer — click to see why▾
Why this is wrong here
Resource locks prevent accidental deletion or modification of resources but do not provide any placement or availability resilience against datacenter outages.
★ When this WOULD be the correct answer
In a scenario where you need to protect critical resources (e.g., a storage account or a virtual network) from accidental deletion or modification by users, a resource lock (CanNotDelete or ReadOnly) would be the correct answer.
Why candidates choose this
Candidates may confuse 'protection' in the question with resource protection mechanisms like locks, rather than understanding it refers to high availability and fault tolerance against datacenter failures.
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
Managed Identities for Azure Resources
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.
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.
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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.