- A
Horizontal scaling
Why wrong: Horizontal scaling (scaling out) involves adding more instances of the same resource, such as deploying additional virtual machines. In this scenario, the team is increasing the capacity of the existing single VM, not adding more VMs.
- B
Vertical scaling
Vertical scaling (scaling up) increases the capacity of a single resource by upgrading its specifications (e.g., more vCPUs, RAM). This matches the action of resizing the VM to a larger SKU.
- C
Diagonal scaling
Why wrong: Diagonal scaling is not a recognized term in cloud computing. Scaling approaches are generally categorized as either vertical (up/down) or horizontal (out/in).
- D
Auto-scaling
Why wrong: Auto-scaling refers to the automated adjustment of resources based on predefined rules or metrics. In this scenario, the resize was performed manually by the IT team, not triggered automatically by a scaling rule.
Quick Answer
The answer is vertical scaling. This is correct because the team increased the VM size from Standard_D2s_v3 to Standard_D8s_v3, adding more vCPUs and RAM to the same single virtual machine, which is the textbook definition of scaling up. Since the application is not designed to run on multiple servers simultaneously, horizontal scaling—which would require distributing the load across multiple instances—is not an option, making vertical scaling the only viable approach. On the Microsoft Azure Fundamentals AZ-900 exam, this scenario tests your ability to distinguish between vertical and horizontal scaling, often using real-world resource constraints like a single-server application. A common trap is confusing scaling up with scaling out; remember that vertical scaling means adding power to one machine, while horizontal scaling means adding more machines. For a quick memory tip, think of vertical scaling as “taller” (more resources on one server) and horizontal scaling as “wider” (more servers side by side).
AZ-900 Describe cloud concepts Practice Question
This AZ-900 practice question tests your understanding of describe cloud concepts. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An IT team manages a customer relationship management (CRM) application hosted on a single Azure virtual machine. As the number of users grows, the CPU and memory usage on the VM consistently exceed 90%. The team decides to increase the VM size from Standard_D2s_v3 (2 vCPUs, 8 GB RAM) to Standard_D8s_v3 (8 vCPUs, 32 GB RAM) to handle the increased load. The application is not designed to run on multiple servers simultaneously. This approach represents which type of scaling in the cloud?
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
Vertical scaling
Increasing the VM size from Standard_D2s_v3 to Standard_D8s_v3 adds more vCPUs and RAM to the same virtual machine, which is the definition of vertical scaling (scaling up). This approach is appropriate because the application cannot run on multiple servers simultaneously, so adding resources to the existing single VM is the only viable option to handle the increased load.
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.
- ✗
Horizontal scaling
Why it's wrong here
Horizontal scaling (scaling out) involves adding more instances of the same resource, such as deploying additional virtual machines. In this scenario, the team is increasing the capacity of the existing single VM, not adding more VMs.
- ✓
Vertical scaling
Why this is correct
Vertical scaling (scaling up) increases the capacity of a single resource by upgrading its specifications (e.g., more vCPUs, RAM). This matches the action of resizing the VM to a larger SKU.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Diagonal scaling
Why it's wrong here
Diagonal scaling is not a recognized term in cloud computing. Scaling approaches are generally categorized as either vertical (up/down) or horizontal (out/in).
- ✗
Auto-scaling
Why it's wrong here
Auto-scaling refers to the automated adjustment of resources based on predefined rules or metrics. In this scenario, the resize was performed manually by the IT team, not triggered automatically by a scaling rule.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse vertical scaling with auto-scaling, but auto-scaling is an automated process that can scale either vertically or horizontally based on rules, whereas this question describes a manual, one-time resizing without any automation.
Trap categories for this question
Scenario analysis trap
Horizontal scaling (scaling out) involves adding more instances of the same resource, such as deploying additional virtual machines. In this scenario, the team is increasing the capacity of the existing single VM, not adding more VMs.
Detailed technical explanation
How to think about this question
Vertical scaling in Azure involves changing the VM's SKU to a larger size within the same series (e.g., Ds_v3), which requires a reboot and may cause a brief downtime. Under the hood, Azure reallocates the VM to a different physical host with more CPU cores and memory, while the OS and application remain unchanged. This contrasts with horizontal scaling, which would require load balancers (e.g., Azure Load Balancer) and stateless application design to distribute traffic across multiple VMs.
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.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this AZ-900 question test?
Describe cloud concepts — This question tests Describe cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Vertical scaling — Increasing the VM size from Standard_D2s_v3 to Standard_D8s_v3 adds more vCPUs and RAM to the same virtual machine, which is the definition of vertical scaling (scaling up). This approach is appropriate because the application cannot run on multiple servers simultaneously, so adding resources to the existing single VM is the only viable option to handle the increased load.
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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Last reviewed: Jun 11, 2026
This AZ-900 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-900 exam.
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