AZ-104 Deploy and Manage Azure Compute Practice Question
A managed data disk on a VM was deleted by mistake. You have a snapshot from before the deletion and want to restore the data with minimal impact to the VM's operating system disk. What should you do?
⚠ Common exam trap
Many exam-takers confuse snapshots with OS disk recovery options, incorrectly assuming a data disk snapshot can be used to boot the VM, or that resizing or redeploying the VM will restore deleted disks.
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
✓
Create a new managed disk from the snapshot and attach it to the VM
You can create a new managed disk from the snapshot and attach it as a data disk to the existing VM. This restores the data without affecting the OS disk or requiring a VM redeployment, minimizing downtime and impact.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create a new managed disk from the snapshot and attach it to the VM
Why this is correct
A managed-disk snapshot is a point-in-time read-only copy of the original data disk. To recover the deleted data disk, you create a new managed disk from that snapshot (specifying the same or larger size and the appropriate storage type) and then attach it to the VM as a data disk. This restores all file contents without re-creating the VM and leaves the existing OS disk untouched, so the VM's identity, name, and attached resources remain consistent.
- ✗
Redeploy the VM from the marketplace image
Why it's wrong here
Redeploying or reimaging from a marketplace image creates a fresh OS disk from the image gallery and replaces the VM's current OS disk; it does not create or attach a data disk from your snapshot. The data that existed on the deleted managed disk is not part of the marketplace image, and Azure does not merge snapshot contents into an image-based deployment. Without first creating a managed disk from the snapshot and attaching it, the data remains inaccessible.
When this WOULD be correct
If the VM's OS disk is corrupted or compromised and you need to quickly restore the VM to its original state without preserving any data or customizations, redeploying from the marketplace image is a valid option.
- ✗
Convert the snapshot directly into an OS disk and boot from it
Why it's wrong here
A data-disk snapshot contains only the file system and partition layout of that data volume, not the boot sector, OS kernel, or BCD store required to boot a Windows or Linux VM. Azure lets you create a new VM from a snapshot, but that snapshot must be an OS-disk snapshot for boot to work. Attempting to 'convert' a data-disk snapshot directly into an OS disk, or swapping it in place of the original OS disk, will yield a non-bootable VM even if the data files are present.
When this WOULD be correct
If the VM's OS disk itself was deleted and you have a snapshot of the OS disk, you could create a managed disk from that snapshot and attach it as the OS disk to a new VM, or use it to replace the existing OS disk (with downtime).
- ✗
Resize the VM to a larger size and the deleted disk will reappear
Why it's wrong here
Resizing a VM changes its hardware profile, such as vCPUs, memory, and the size of any temporary storage, but it does not enumerate, rehydrate, or restore storage objects that were deleted from the subscription. A deleted managed disk is permanently removed from the Azure Resource Manager resource set; a snapshot, if one exists, is an independent resource that must be explicitly used to create a new disk. No VM resize operation triggers automatic disk recovery or reattaches a deleted data disk from a snapshot.
When this WOULD be correct
If a VM is experiencing performance issues due to insufficient disk throughput, resizing the VM to a larger size can increase the disk performance limits, potentially resolving the issue.
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.
✓Create a new managed disk from the snapshot and attach it to the VMCorrect answer▾
Why this is correct
A managed-disk snapshot is a point-in-time read-only copy of the original data disk. To recover the deleted data disk, you create a new managed disk from that snapshot (specifying the same or larger size and the appropriate storage type) and then attach it to the VM as a data disk. This restores all file contents without re-creating the VM and leaves the existing OS disk untouched, so the VM's identity, name, and attached resources remain consistent.
✗Redeploy the VM from the marketplace imageWrong answer — click to see why▾
Why this is wrong here
Redeploying the VM from a marketplace image would replace the entire OS disk with a fresh image, losing all data and customizations, and does not restore the deleted data disk.
★ When this WOULD be the correct answer
If the VM's OS disk is corrupted or compromised and you need to quickly restore the VM to its original state without preserving any data or customizations, redeploying from the marketplace image is a valid option.
Why candidates choose this
Candidates may think redeploying is a quick fix to restore the VM, not realizing it wipes the OS disk and does not recover the deleted data disk.
✗Convert the snapshot directly into an OS disk and boot from itWrong answer — click to see why▾
Why this is wrong here
Converting a snapshot into an OS disk and booting from it would replace the VM's operating system disk, causing significant disruption and potential data loss on the OS disk, whereas the question asks to restore a data disk with minimal impact to the OS disk.
★ When this WOULD be the correct answer
If the VM's OS disk itself was deleted and you have a snapshot of the OS disk, you could create a managed disk from that snapshot and attach it as the OS disk to a new VM, or use it to replace the existing OS disk (with downtime).
Why candidates choose this
Candidates may think that since snapshots can create disks, directly using a snapshot as an OS disk is a quick fix, overlooking that the snapshot is from a data disk and that booting from it would replace the OS disk, causing major disruption.
✗Resize the VM to a larger size and the deleted disk will reappearWrong answer — click to see why▾
Why this is wrong here
Resizing a VM does not recover deleted disks; disks are independent resources and must be recreated from snapshots or backups.
★ When this WOULD be the correct answer
If a VM is experiencing performance issues due to insufficient disk throughput, resizing the VM to a larger size can increase the disk performance limits, potentially resolving the issue.
Why candidates choose this
Candidates may mistakenly think that disk resizing or VM operations can restore deleted disks, confusing disk management with VM lifecycle operations.
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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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.