AZ-104 Deploy and Manage Azure Compute Practice Question
An administrator has already increased the size of a managed data disk attached to a running Windows VM. Azure now shows the larger disk size, but the application still cannot use the new capacity. What should the administrator do next?
⚠ Common exam trap
Many exam-takers assume Azure automatically applies the size change to the guest OS, when in fact the administrator must manually extend the partition inside the operating system using disk management tools.
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
✓
Expand the partition or volume inside the guest operating system.
When a managed data disk attached to a running Windows VM is resized in Azure, the underlying virtual hard disk (VHD) expands, but the guest operating system does not automatically recognize the new unallocated space. The administrator must use the Disk Management tool (diskmgmt.msc) or the diskpart command to extend the volume or partition into the unallocated space. This is a standard operating system task, not an Azure control-plane action.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Detach the disk, shrink it, and reattach it to refresh the filesystem.
Why it's wrong here
Detaching the disk and reattaching it would not refresh the filesystem nor resize the partition; it would simply remount the same volume. Shrinking the disk would reduce capacity, which is the opposite of the goal, and detaching a data disk from a running VM risks downtime to the application. The only way to use the new space is to extend the volume inside the OS, e.g., via Diskpart or PowerShell.
When this WOULD be correct
If the question stated that the disk was over-provisioned and needed to be reduced to save costs, or if the disk was corrupted and needed to be reinitialized after shrinking to a smaller size, then detaching, shrinking, and reattaching might be part of the process.
- ✓
Expand the partition or volume inside the guest operating system.
Why this is correct
After Azure grows the managed disk, the operating system still needs to recognize and consume that extra space. Expanding the partition or volume inside the guest OS is the required next step so the application can use the larger capacity.
- ✗
Convert the data disk to a shared disk so Windows can auto-detect the size increase.
Why it's wrong here
Converting the data disk to a shared disk changes its attachment model to support multiple VMs in a cluster, but it has no effect on the partition size recognized by the guest OS. In fact, converting requires the disk to be detached and may impose limitations; it is completely orthogonal to resizing a volume. The guest still needs an explicit volume extension step (e.g., Resize-Partition) to use the added capacity.
When this WOULD be correct
When you need to attach the same managed disk to multiple VMs for clustered applications (e.g., SQL Server FCI, Scale-out File Server). In that scenario, enabling shared disk allows concurrent read/write from multiple VMs.
- ✗
Redeploy the virtual machine to apply the new disk size.
Why it's wrong here
Redeploying the VM only migrates it to a new host node; it does not trigger the guest OS to rescan or extend the partition. The Azure disk has already been resized at the platform level, but the volume inside Windows remains unchanged until you use Disk Management or PowerShell to extend it. Hence a redeploy is both disruptive and ineffective for consuming the new capacity.
When this WOULD be correct
If a VM is experiencing hardware-level issues (e.g., host failure, connectivity problems) and you need to restore it to a healthy host, redeploying is the correct action.
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.
✓Expand the partition or volume inside the guest operating system.Correct answer▾
Why this is correct
After Azure grows the managed disk, the operating system still needs to recognize and consume that extra space. Expanding the partition or volume inside the guest OS is the required next step so the application can use the larger capacity.
✗Detach the disk, shrink it, and reattach it to refresh the filesystem.Wrong answer — click to see why▾
Why this is wrong here
Shrinking the disk would reduce capacity, not help the OS recognize the increased size. The filesystem refresh is not achieved by detaching and shrinking; the OS must extend the partition to use the new space.
★ When this WOULD be the correct answer
If the question stated that the disk was over-provisioned and needed to be reduced to save costs, or if the disk was corrupted and needed to be reinitialized after shrinking to a smaller size, then detaching, shrinking, and reattaching might be part of the process.
Why candidates choose this
Candidates may think that detaching and reattaching forces the OS to re-scan the disk and recognize the new size, similar to how a reboot can refresh hardware detection, but this is not the case for partition size changes.
✗Convert the data disk to a shared disk so Windows can auto-detect the size increase.Wrong answer — click to see why▾
Why this is wrong here
Converting a data disk to a shared disk does not cause Windows to auto-detect a size increase; shared disks are for multi-VM access, not for resizing. The guest OS still requires manual partition expansion.
★ When this WOULD be the correct answer
When you need to attach the same managed disk to multiple VMs for clustered applications (e.g., SQL Server FCI, Scale-out File Server). In that scenario, enabling shared disk allows concurrent read/write from multiple VMs.
Why candidates choose this
Candidates may think 'shared' implies automatic synchronization or detection of changes, or they confuse the disk sharing feature with automatic resizing capabilities.
✗Redeploy the virtual machine to apply the new disk size.Wrong answer — click to see why▾
Why this is wrong here
Redeploying a VM moves it to a new host but does not resize or refresh the disk partition inside the guest OS; the OS still sees the old partition size.
★ When this WOULD be the correct answer
If a VM is experiencing hardware-level issues (e.g., host failure, connectivity problems) and you need to restore it to a healthy host, redeploying is the correct action.
Why candidates choose this
Candidates may think redeploying refreshes all VM resources, similar to rebooting, and assume it will apply the new disk size automatically.
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?”
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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. Based on the exhibit, what should the administrator do next so the VM can use the extra capacity on the resized data disk?
easy- A.Resize the managed disk again in Azure.
- ✓ B.Extend the partition or file system inside the VM.
- C.Detach the disk and attach it to another VM.
- D.Create a new virtual machine from the disk.
Why B: After resizing a managed disk in Azure, the additional capacity is allocated at the Azure platform level but is not automatically available to the operating system. The administrator must extend the partition or file system inside the VM using tools like Diskpart (Windows) or fdisk/resize2fs (Linux) to make the new space usable. This is a standard post-resize step because the OS still sees the original partition boundaries.
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.