The answer is the Ephemeral OS disk. This is correct because an ephemeral OS disk uses the local VM storage, typically an NVMe SSD physically attached to the host server, rather than a remote Azure managed disk. This direct attachment eliminates network round trips for read and write operations, providing the lowest possible latency for the OS disk, which is critical for a development VM that is rebuilt often and does not require disk persistence. On the AZ-104 exam, this question tests your understanding of the trade-off between performance and durability; a common trap is choosing a Premium SSD managed disk for speed, but that still incurs network latency compared to local storage. Remember the key condition: if the VM is temporary and deallocated frequently, the ephemeral disk wins on latency. Memory tip: “Ephemeral equals local, local equals fastest—if you can lose it, use it.”
AZ-104 Deploy and Manage Azure Compute Practice Question
This AZ-104 practice question tests your understanding of deploy and manage azure compute. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A development VM is rebuilt often and does not need its operating system disk contents to survive deallocation. The team wants the lowest practical disk latency for the OS. Which disk option should the administrator choose?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Ephemeral OS disk
Ephemeral OS disks use the local VM storage (SSD) rather than Azure managed disks, providing the lowest latency for OS read/write operations. Since the VM is rebuilt often and disk persistence is not required, the ephemeral disk is ideal because its contents are lost when the VM is deallocated, eliminating the need for a separate managed disk.
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.
✗
Standard HDD managed disk
Why it's wrong here
Standard HDD is economical, but it provides lower performance and higher latency than the other options.
✓
Ephemeral OS disk
Why this is correct
An ephemeral OS disk is stored on the host and offers very low latency, which fits temporary or rebuildable VMs.
Related concept
Read the scenario before looking for a memorised answer.
✗
Geo-redundant storage for the OS disk
Why it's wrong here
Geo-redundancy is a storage replication concept, not the best answer for local OS disk latency.
✗
A data disk formatted as the boot disk
Why it's wrong here
Using a data disk as a boot disk is not the normal Azure VM deployment pattern.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Standard HDD (Option A) thinking it is the cheapest option, but they overlook that 'lowest practical disk latency' explicitly requires performance, not cost, and that Ephemeral OS disks provide both low latency and zero cost for the OS disk itself (since it uses local storage).
Detailed technical explanation
How to think about this question
Ephemeral OS disks are backed by the local NVMe SSD of the Azure host, which is directly attached to the server, bypassing the network storage fabric used by managed disks. This results in IOPS and latency comparable to the underlying hardware (e.g., up to 170,000 IOPS on certain VM sizes). However, the disk size is limited to the cache/temp storage capacity of the VM SKU, and the disk is not durable—any deallocation or stop of the VM destroys the data, making it perfect for stateless workloads like dev/test or container hosts.
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
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: Ephemeral OS disk — Ephemeral OS disks use the local VM storage (SSD) rather than Azure managed disks, providing the lowest latency for OS read/write operations. Since the VM is rebuilt often and disk persistence is not required, the ephemeral disk is ideal because its contents are lost when the VM is deallocated, eliminating the need for a separate managed disk.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 development environment uses temporary test VMs that can be rebuilt at any time. The administrator wants the operating system disk to provide the lowest practical latency and does not need the disk data to survive a deallocate operation. Which OS disk option should be selected?
medium
A.Standard HDD managed disk.
B.Premium SSD managed disk.
✓ C.Ephemeral OS disk.
D.Ultra Disk managed disk.
Why C: Ephemeral OS disks use the local VM storage (temporary disk) rather than remote managed storage, which provides the lowest possible latency because data is stored directly on the host node. Since the test VMs can be rebuilt at any time and the disk data does not need to survive a deallocate operation, the ephemeral disk is ideal—it is automatically deleted when the VM is deallocated or deleted, and it avoids the cost and performance overhead of managed disks.
Variation 2. A development VM is recreated from scratch every week. The team wants the operating system disk to boot as quickly as possible and does not need the OS disk contents to survive deallocation. Which disk choice should the administrator make?
hard
A.A Premium SSD managed OS disk
✓ B.An ephemeral OS disk
C.A Standard SSD managed OS disk
D.The VM temporary disk as the operating system disk
Why B: An ephemeral OS disk is created on the local VM host storage, not on Azure managed storage, which eliminates network latency and provides significantly faster boot times. Since the team does not need the OS disk contents to survive deallocation and recreates the VM weekly, ephemeral disks are ideal as they are reset to the original image state on each deployment.
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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.
Question Discussion
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