Question 310 of 1,170
Deploy and Manage Azure ComputemediumMultiple SelectObjective-mapped

How to Set Up VMSS Autoscale with CPU Thresholds and Instance Limits

This AZ-104 practice question tests your understanding of deploy and manage azure compute. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.

The operations team wants 3 to 8 identical Linux VM instances, with more instances added when average CPU stays above 70 percent for 10 minutes and removed when load falls. Which three settings should be configured? Select three.

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

Use a virtual machine scale set for the identical application instances.

A virtual machine scale set (VMSS) is the correct Azure service for deploying and managing a group of identical, load-balanced Linux VMs that can automatically scale in and out based on demand. It supports autoscaling rules that adjust the instance count within a defined range, meeting the requirement for 3 to 8 identical instances with automatic addition when average CPU exceeds 70% for 10 minutes and removal when load falls.

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.

  • Use a virtual machine scale set for the identical application instances.

    Why this is correct

    A VM scale set is the compute service built for multiple identical instances with centralized scaling and management. It is the correct foundation for a workload that expands and contracts over time.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Create an autoscale profile with a scale-out rule based on average CPU utilization.

    Why this is correct

    The autoscale profile is where the CPU threshold and evaluation window are defined. A scale-out rule tied to average CPU above 70 percent for 10 minutes matches the business requirement precisely.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Set minimum and maximum instance counts so the service cannot scale below 3 or above 8.

    Why this is correct

    Minimum and maximum bounds keep autoscale within the required operating range. They prevent over-scaling costs and ensure the service always keeps at least the minimum capacity online.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Place the VMs in an availability set instead of using a scale set.

    Why it's wrong here

    An availability set improves resilience, but it does not provide built-in horizontal autoscaling. It would not meet the requirement to add and remove instances automatically based on CPU usage.

    When this WOULD be correct

    If the question required high availability for a fixed number of VMs (e.g., 3 VMs) without autoscaling, and the goal was to protect against hardware failures, an availability set would be the correct choice.

  • Clone the VM manually whenever CPU rises and remove clones by hand later.

    Why it's wrong here

    Manual cloning is slow, error-prone, and defeats the goal of automatic scaling. It also makes it harder to maintain identical configuration across instances over time.

    When this WOULD be correct

    This option would be correct in a scenario where the question specifies a small, static number of VMs (e.g., exactly 3) with no autoscaling requirement, and the candidate is asked to choose a manual deployment method for identical instances.

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.

Use a virtual machine scale set for the identical application instances.Correct answer

Why this is correct

A VM scale set is the compute service built for multiple identical instances with centralized scaling and management. It is the correct foundation for a workload that expands and contracts over time.

Place the VMs in an availability set instead of using a scale set.Wrong answer — click to see why

Why this is wrong here

An availability set provides high availability for VMs but does not support autoscaling; it cannot automatically add or remove instances based on CPU load, which is required by the question.

★ When this WOULD be the correct answer

If the question required high availability for a fixed number of VMs (e.g., 3 VMs) without autoscaling, and the goal was to protect against hardware failures, an availability set would be the correct choice.

Why candidates choose this

Candidates may confuse availability sets with scale sets, thinking both provide scaling, or they may focus on high availability and overlook the explicit autoscaling requirement.

Clone the VM manually whenever CPU rises and remove clones by hand later.Wrong answer — click to see why

Why this is wrong here

Manual cloning and removal does not meet the requirement for automated scaling based on CPU thresholds; it lacks the autoscaling and orchestration capabilities of a scale set.

★ When this WOULD be the correct answer

This option would be correct in a scenario where the question specifies a small, static number of VMs (e.g., exactly 3) with no autoscaling requirement, and the candidate is asked to choose a manual deployment method for identical instances.

Why candidates choose this

Candidates may think manual cloning is a valid way to handle scaling for a small number of VMs, overlooking the automation and elasticity requirements in the question.

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?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates may confuse availability sets with scale sets, thinking both provide scaling, but availability sets only offer redundancy and fault tolerance, not automatic scaling or instance count management.

Detailed technical explanation

How to think about this question

Azure VMSS uses an autoscale profile with metrics-based rules, where the scale-out rule triggers when the average CPU percentage across all instances exceeds 70% for a 10-minute duration (using the 'Average' statistic and a 10-minute time grain). The scale-in rule similarly reduces instances when CPU drops below a threshold, and the minimum and maximum instance counts (3 and 8) are enforced by the autoscale profile to prevent over- or under-provisioning. Under the hood, VMSS leverages Azure Monitor autoscale with a cooldown period (default 5 minutes) to avoid flapping, ensuring stability during scaling events.

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.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this AZ-104 question test?

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: Use a virtual machine scale set for the identical application instances. — A virtual machine scale set (VMSS) is the correct Azure service for deploying and managing a group of identical, load-balanced Linux VMs that can automatically scale in and out based on demand. It supports autoscaling rules that adjust the instance count within a defined range, meeting the requirement for 3 to 8 identical instances with automatic addition when average CPU exceeds 70% for 10 minutes and removal when load falls.

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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Same concept, more angles

2 more ways this is tested on AZ-104

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. You have a virtual machine scale set that must increase the number of instances automatically when average CPU utilization exceeds 75 percent and decrease when utilization drops below 30 percent. What should you configure?

hard
  • A.An Azure Monitor autoscale rule on the scale set
  • B.A boot diagnostics configuration
  • C.An availability set
  • D.A custom script extension

Why A: Azure Monitor autoscale rules allow you to define conditions for automatically scaling out (increasing instances) when average CPU utilization exceeds a threshold (e.g., 75%) and scaling in (decreasing instances) when it drops below a lower threshold (e.g., 30%). These rules are applied directly to the virtual machine scale set, enabling dynamic scaling based on performance metrics.

Variation 2. A stateless Linux API should start with 2 instances, scale out to 6 when average CPU stays above 75 percent for 10 minutes, and scale back in when load drops. Which Azure compute resource should the administrator deploy?

medium
  • A.An availability set with manual VM resizing.
  • B.A virtual machine scale set with autoscale rules.
  • C.A single Standard D-series VM with scheduled shutdown.
  • D.A load balancer in front of two unmanaged VMs.

Why B: A virtual machine scale set (VMSS) with autoscale rules is the correct choice because it natively supports scaling out and scaling in based on performance metrics like average CPU percentage. The requirement for a stateless Linux API with a minimum of 2 instances, scaling to 6 when CPU exceeds 75% for 10 minutes, and scaling back in when load drops is exactly the use case VMSS is designed for. Autoscale rules can be configured to use a scale-out and scale-in policy with a cool-down period, ensuring the application remains responsive while optimizing cost.

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Last reviewed: Jun 11, 2026

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