The answer is a snapshot. A snapshot creates a point-in-time, read-only copy of a managed or unmanaged disk without detaching it or requiring the VM to be stopped, which is exactly what you need before altering a production data disk. Unlike a backup, which is designed for long-term retention and disaster recovery across regions, a snapshot is a lightweight, incremental copy stored in the same region that can be used to instantly restore the original disk or spin up a new one—all while the VM continues running. On the AZ-104 exam, this question tests your ability to differentiate between Azure Disk Snapshot and Backup scenarios; a common trap is choosing "backup" because it sounds safer, but backups require a Recovery Services vault and are not meant for quick, non-disruptive point-in-time copies before a change. Remember the memory tip: "Snapshot for surgery, Backup for insurance"—use a snapshot when you need to make a precise, immediate copy before modifying a disk, and save backups for scheduled, long-term protection.
AZ-104 Deploy and Manage Azure Compute Practice Question
This AZ-104 practice question tests your understanding of deploy and manage azure compute. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Before changing a production VM's data disk, you want a point-in-time copy that can be restored later without affecting the VM. What should you create?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Snapshot
A snapshot captures a point-in-time, read-only copy of a managed or unmanaged disk. It can be used to create a new disk or restore the original disk without affecting the running VM, making it the correct choice for a non-disruptive backup before a data disk change.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Snapshot
Why this is correct
A snapshot creates a point-in-time copy of a managed disk and can be used to restore or create a new disk later.
Related concept
Read the scenario before looking for a memorised answer.
✗
Availability set
Why it's wrong here
An availability set improves VM resilience, but it does not capture disk contents.
✗
Azure Policy assignment
Why it's wrong here
Policy can enforce rules, but it does not create a disk copy for recovery.
✗
Virtual network peering
Why it's wrong here
Peering connects networks, but it has nothing to do with preserving disk state.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse a snapshot with a backup vault or recovery services vault, but the question specifically asks for a point-in-time copy that does not affect the running VM, and only a snapshot meets that requirement without requiring a backup policy or agent.
Detailed technical explanation
How to think about this question
When you take a snapshot of a managed disk, Azure creates a read-only copy of the disk at that instant, using a differential snapshot mechanism that only stores changes since the last snapshot (if incremental snapshots are enabled). This allows you to later create a new managed disk from the snapshot and attach it to the same or a different VM, effectively restoring the data without downtime for the original VM. In a real-world scenario, you might snapshot a data disk before applying a critical patch, then if the patch fails, you can detach the current disk and attach a new disk created from the snapshot to roll back.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-104 question in full detail.
Deploy and Manage Azure Compute — This question tests Deploy and Manage Azure Compute — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Snapshot — A snapshot captures a point-in-time, read-only copy of a managed or unmanaged disk. It can be used to create a new disk or restore the original disk without affecting the running VM, making it the correct choice for a non-disruptive backup before a data disk change.
What should I do if I get this AZ-104 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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