Ultra Disk is the correct choice because it delivers the highest IOPS and throughput of any Azure managed disk, with sub-millisecond latency, making it ideal for high-performance transactional workloads. This disk type supports up to 160,000 IOPS and 2,000 MB/s throughput per disk, and uniquely allows you to independently scale IOPS and throughput without swapping the disk. On the AZ-900 exam, this question tests your understanding of Azure storage performance tiers, and a common trap is confusing Premium SSD with Ultra Disk—remember that Premium SSD offers high performance but cannot match Ultra Disk’s maximum IOPS and throughput, nor its sub-millisecond latency. The exam expects you to recognize that for the absolute highest storage performance, Ultra Disk is the only answer. A helpful memory tip: think “Ultra = Ultimate IOPS and Throughput.”
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. 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 company has a virtual machine running a legacy application that needs high-performance, low-latency storage for transactional data. They need to attach a storage solution that provides the highest IOPS and throughput. Which Azure managed disk type should they choose?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
D) Ultra Disk
Ultra Disk is the correct choice because it offers the highest IOPS and throughput of any Azure managed disk, with sub-millisecond latency, making it ideal for high-performance, low-latency transactional workloads. It supports up to 160,000 IOPS and 2,000 MB/s throughput per disk, and allows independent scaling of IOPS and throughput without requiring a disk swap.
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.
✗
A) Standard HDD
Why it's wrong here
Standard HDD offers the lowest IOPS and throughput, not suitable for high-performance needs.
✗
B) Standard SSD
Why it's wrong here
Standard SSD provides moderate performance but not the highest IOPS.
✗
C) Premium SSD
Why it's wrong here
Premium SSD offers high performance but Ultra Disk provides even higher IOPS and lower latency.
✓
D) Ultra Disk
Why this is correct
Ultra Disk offers sub-millisecond latency and up to 160,000 IOPS per disk, meeting the highest performance requirements.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Premium SSD (Option C) because it is the most familiar high-performance disk type, but they overlook Ultra Disk's superior IOPS and throughput capabilities, which are explicitly required for the 'highest' performance scenario described in the question.
Detailed technical explanation
How to think about this question
Ultra Disk uses a distributed storage fabric with NVMe over RDMA (Remote Direct Memory Access) to achieve consistent sub-millisecond latency and extreme performance, unlike Premium SSD which relies on SCSI-based protocols. A real-world scenario is a high-frequency trading system or a large SQL Server database that requires both high IOPS for random reads/writes and high throughput for sequential operations, where Ultra Disk's ability to dynamically adjust performance without downtime is critical. Under the hood, Ultra Disk performance is provisioned at the disk level (not per VM size), allowing up to 256 MB/s per vCPU for throughput scaling.
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-900 question in full detail.
Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: D) Ultra Disk — Ultra Disk is the correct choice because it offers the highest IOPS and throughput of any Azure managed disk, with sub-millisecond latency, making it ideal for high-performance, low-latency transactional workloads. It supports up to 160,000 IOPS and 2,000 MB/s throughput per disk, and allows independent scaling of IOPS and throughput without requiring a disk swap.
What should I do if I get this AZ-900 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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