Single VM in Availability Zone for Datacenter Failure
A line-of-business app will run on a single Azure virtual machine in a region that supports availability zones. The business wants the VM to keep running if one datacenter in the region fails. Which deployment choice should you use?
Quick Answer
The answer is to deploy the VM in an availability zone. This is correct because availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking; placing a single VM in one zone ensures that if a different datacenter in the region fails, your VM remains operational since it is hosted in a separate, unaffected zone. On the AZ-104 exam, this scenario tests your understanding of high availability versus fault tolerance—a common trap is confusing an availability set (which protects against rack-level failures within one datacenter) with an availability zone (which protects against a full datacenter failure). Remember that an availability set spreads VMs across fault domains inside a single datacenter, while an availability zone isolates the VM to an entire separate datacenter. A useful memory tip: “Zone for datacenter doom, set for rack-room gloom.”
⚠ Common exam trap
Many exam-takers confuse availability sets (which protect against rack-level failures within a datacenter) with availability zones (which protect against entire datacenter failures), leading them to incorrectly select availability set as the answer.
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
✓
Deploy the VM in an availability zone
Availability zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. Deploying the VM in an an availability zone ensures that if one datacenter fails, the VM remains operational because it is hosted in a different zone. This directly meets the requirement for resilience against a single datacenter failure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Place the VM in an availability set
Why it's wrong here
An availability set protects against certain maintenance and host failures, but it does not place the VM in separate datacenter zones.
When this WOULD be correct
If the question asked for protection against hardware failures or maintenance events within a single datacenter (e.g., 'The VM must remain available during planned maintenance within the same datacenter'), then placing the VM in an availability set would be correct.
- ✓
Deploy the VM in an availability zone
Why this is correct
An availability zone places the VM in a physically separate datacenter within the same Azure region. That design gives better resilience against a datacenter-level failure than an availability set. For a single VM, choosing a zone is the direct way to improve protection from one zone or datacenter going offline. It is the right operational choice when the region supports zones and the requirement is survivability during a datacenter outage.
- ✗
Use a larger VM size
Why it's wrong here
A larger VM size can improve performance, but it does not add redundancy or protect against datacenter failure.
When this WOULD be correct
A question where the business requires higher compute or memory capacity for a VM, and the exam asks which VM size tier (e.g., Standard_D2s_v3 vs Standard_D4s_v3) to choose to meet performance requirements.
- ✗
Use a custom image
Why it's wrong here
A custom image helps standardize software installation, but it does not provide resilience against infrastructure failure.
When this WOULD be correct
A question asks: 'You need to deploy multiple VMs with a specific pre-configured software stack. Which approach ensures consistent configuration across all VMs?' Using a custom image would be correct to capture the exact configuration and deploy it repeatedly.
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.
✓Deploy the VM in an availability zoneCorrect answer▾
Why this is correct
An availability zone places the VM in a physically separate datacenter within the same Azure region. That design gives better resilience against a datacenter-level failure than an availability set. For a single VM, choosing a zone is the direct way to improve protection from one zone or datacenter going offline. It is the right operational choice when the region supports zones and the requirement is survivability during a datacenter outage.
✗Place the VM in an availability setWrong answer — click to see why▾
Why this is wrong here
An availability set protects against failures within a single datacenter (e.g., rack or update domain failures), not against a full datacenter outage. Since the requirement is to survive a datacenter failure, availability zones (which span separate datacenters) are needed.
★ When this WOULD be the correct answer
If the question asked for protection against hardware failures or maintenance events within a single datacenter (e.g., 'The VM must remain available during planned maintenance within the same datacenter'), then placing the VM in an availability set would be correct.
Why candidates choose this
Candidates may confuse availability sets with availability zones, thinking both provide datacenter-level fault tolerance, or they may recall that availability sets offer high availability without realizing they are limited to a single datacenter.
✗Use a larger VM sizeWrong answer — click to see why▾
Why this is wrong here
Increasing VM size improves performance but does not provide datacenter-level fault tolerance; it only adds more resources within the same datacenter.
★ When this WOULD be the correct answer
A question where the business requires higher compute or memory capacity for a VM, and the exam asks which VM size tier (e.g., Standard_D2s_v3 vs Standard_D4s_v3) to choose to meet performance requirements.
Why candidates choose this
Candidates may mistakenly believe that a larger VM size inherently includes redundancy or high availability features, confusing scalability with fault tolerance.
✗Use a custom imageWrong answer — click to see why▾
Why this is wrong here
Using a custom image does not provide any datacenter-level redundancy; it only defines the OS and software configuration of the VM, not its placement or fault tolerance.
★ When this WOULD be the correct answer
A question asks: 'You need to deploy multiple VMs with a specific pre-configured software stack. Which approach ensures consistent configuration across all VMs?' Using a custom image would be correct to capture the exact configuration and deploy it repeatedly.
Why candidates choose this
Candidates may think a custom image can be used to deploy VMs in different datacenters, but it does not affect availability or fault tolerance.
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
Azure virtual machine
An Azure virtual machine is a software-based emulation of a physical computer that runs in Microsoft's cloud, allowing you to deploy and manage applications without owning the hardware.
Key term
Availability zone
An Availability Zone is a distinct, isolated location within a cloud region that contains its own power, cooling, and networking, designed to protect applications from single points of failure.
About these practice questions
This AZ-104 question is part of Courseiva's 1,049-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on AZ-104
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A line-of-business app runs on a single Azure VM in a region that supports availability zones. The business wants the VM to keep running if one datacenter in the region becomes unavailable. Which deployment choice best meets this requirement?
easy- A.Availability set
- ✓ B.Availability zone
- C.Proximity placement group
- D.Virtual machine scale set
Why B: An availability zone is a physically separate datacenter within an Azure region, with independent power, cooling, and networking. Deploying the VM to a specific zone ensures it remains operational if another zone's datacenter fails, meeting the requirement for single-VM resilience against a datacenter outage.
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.