AZ-900 Describe cloud concepts Practice Test 13 — 15 Questions

Question 1

A company runs a web application on Azure virtual machines. During a promotional event, the number of users increases significantly. To handle the increased load, the IT team adds five additional virtual machines to the existing pool, so that the total number of VMs increases from three to eight. Which type of scaling is the team using?

Accepted Answer

Horizontal scaling (scale out). Horizontal scaling (scale out) involves increasing the number of virtual machines (VMs) in a pool to distribute load, as seen when the team adds five VMs to go from three to eight. This approach improves capacity by adding more instances, rather than increasing the size of existing ones. In Azure, this is commonly achieved using Virtual Machine Scale Sets or Azure Load Balancer to distribute traffic across the expanded pool.

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Vertical scaling (scale up)

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Elasticity

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High availability

Question 2

A multinational company is expanding its online retail business to new countries. The company needs to deploy its web application in Azure regions that are geographically close to customers in Europe, Asia, and North America to minimize latency. The IT team can deploy identical application instances in multiple regions within minutes using Azure Resource Manager templates. Which benefit of cloud computing does this scenario best illustrate?

Accepted Answer

Global reach. Option C is correct because the scenario emphasizes deploying identical application instances in multiple Azure regions across Europe, Asia, and North America to serve customers geographically close to each region, which directly illustrates the global reach benefit of cloud computing. Azure Resource Manager (ARM) templates enable rapid, consistent deployment to any region, allowing the company to expand its global footprint and reduce latency by leveraging Azure's distributed infrastructure.

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High availability

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Elasticity

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Disaster recovery

Question 3

A company currently runs its application on-premises in a data center. The IT manager calculates that the cost per server per month is approximately $200 when considering hardware depreciation, electricity, cooling, and staff. The company is considering moving to Azure and discovers that Azure can provision the same server capacity for $150 per month, but only if the company commits to a three-year reservation. Which cloud concept best explains why Azure can offer a lower price even with the reservation commitment?

Accepted Answer

Economies of scale. Azure can offer a lower price for a three-year reserved instance because of economies of scale. Microsoft operates massive, globally distributed data centers that purchase hardware, power, and cooling in bulk, significantly reducing per-unit costs. This cost advantage is passed to customers who commit to longer-term reservations, as the provider can better predict and optimize resource utilization.

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Rapid elasticity

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High availability

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Measured service

Question 4

A company runs a development and testing environment on Azure virtual machines. The environment is only needed during standard business hours (9:00 AM to 5:00 PM), Monday through Friday. The IT team configures an automated schedule that deallocates all VMs at 5:00 PM each weekday and starts them again at 8:00 AM the next morning. The team reports a significant reduction in their monthly Azure bill after implementing this schedule. Which essential characteristic of cloud computing does this scenario primarily demonstrate?

Accepted Answer

Measured service and consumption-based pricing. The scenario demonstrates measured service and consumption-based pricing because Azure charges for VM compute costs only when the VM is in the 'Running' state. Deallocating the VM releases the reserved compute resources, stopping billing for the VM's vCPU and RAM while retaining the disk and other resources. By scheduling deallocation outside business hours, the company pays only for the hours the VMs are actually running, directly reducing costs based on usage.

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Rapid elasticity and scaling

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High availability

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Geographic distribution

Question 5

What is the primary benefit of high availability in cloud computing?

Accepted Answer

Ensuring services remain operational with minimal downtime. High availability (HA) in cloud computing is designed to ensure that services and applications remain operational with minimal downtime, typically targeting a specific uptime percentage (e.g., 99.99% or 'four nines'). This is achieved through redundancy, failover mechanisms, and load balancing across multiple availability zones or regions, so that if one component fails, another takes over without significant interruption. The primary benefit is business continuity and service reliability, not cost reduction or performance scaling.

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Reducing the cost of compute resources

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Automatically scaling resources during peak demand

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Distributing content to users geographically

Question 6

In the shared responsibility model for cloud computing, which responsibility always remains with the customer regardless of the cloud service type?

Accepted Answer

Managing data and access identities. Under the shared responsibility model, the customer is always responsible for managing data and access identities, regardless of whether the service is IaaS, PaaS, or SaaS. This includes classifying data, encrypting data at rest and in transit, and configuring identity and access management (IAM) policies. Even in SaaS, where the provider manages the application, the customer must control who has access and how data is protected.

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Managing physical network infrastructure

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Patching the underlying hypervisor

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Maintaining operating system patches

Question 7

Which cloud service model gives customers the most control over the underlying infrastructure, including the operating system and networking?

Accepted Answer

Infrastructure as a Service (IaaS). Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, giving customers direct control over the operating system, storage, and networking components such as virtual networks and firewalls. Unlike higher-level service models, IaaS allows users to manage and configure the underlying infrastructure without physical hardware access, making it the model with the most customer control.

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Software as a Service (SaaS)

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Platform as a Service (PaaS)

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Function as a Service (FaaS)

Question 8

What is 'scalability' in the context of cloud computing?

Accepted Answer

The ability to increase or decrease resources to match demand. Scalability in cloud computing refers to the ability to dynamically adjust resources (such as compute power, memory, or storage) to match fluctuating demand. This is a core benefit of cloud platforms like Azure, enabling automatic scaling via services such as Azure Virtual Machine Scale Sets or Azure App Service autoscale, ensuring performance without over-provisioning.

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The ability to keep services running during failures

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The ability to recover data after a disaster

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The ability to deploy resources in multiple geographic regions

Question 9

Which type of cloud deployment model uses a combination of on-premises infrastructure and public cloud services?

Accepted Answer

Hybrid cloud. Option C is correct because a hybrid cloud deployment model explicitly combines on-premises infrastructure (private cloud or local datacenter) with public cloud services, allowing data and applications to be shared between them. This enables organizations to keep sensitive workloads on-premises while leveraging the scalability of public cloud for burst capacity or less critical workloads, often connected via VPN or dedicated circuits like Azure ExpressRoute.

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Public cloud

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Private cloud

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Multi-cloud

Question 10

What is 'agility' in the context of cloud computing?

Accepted Answer

The ability to quickly deploy and configure resources to meet business needs. Agility in cloud computing refers to the ability to rapidly provision, scale, and decommission resources (such as virtual machines, databases, or containers) to adapt to changing business demands. This is enabled by infrastructure-as-code (IaC) tools like Azure Resource Manager (ARM) templates, which allow you to deploy and configure resources in minutes rather than weeks, directly supporting business responsiveness.

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The ability to protect data from unauthorized access

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The ability to run applications across multiple cloud providers

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The ability to store data permanently without loss

Question 11

What is the benefit of 'economies of scale' in cloud computing?

Accepted Answer

Cloud providers pass on lower per-unit costs from massive purchasing power to customers. Economies of scale in cloud computing refers to the cost advantage that cloud providers achieve through massive purchasing power—buying hardware, bandwidth, and power in bulk at discounted rates. They then pass these savings on to customers in the form of lower per-unit costs for compute, storage, and networking services. This is a fundamental economic principle that makes public cloud more cost-effective than running your own data center.

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You can deploy resources in any geographic location worldwide

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You can scale your resources up or down to match demand

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You avoid the cost of managing physical infrastructure

Question 12

Which cloud computing characteristic allows an organization to avoid purchasing excess capacity to handle occasional peak loads?

Accepted Answer

Elasticity. Elasticity is the cloud computing characteristic that allows resources to automatically scale up to meet peak demand and scale down when demand decreases, so organizations only pay for what they use and avoid over-provisioning. This eliminates the need to purchase and maintain excess capacity for occasional load spikes, as the cloud provider dynamically allocates resources in real time.

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High availability

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Geo-distribution

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Durability

Question 13

Which Azure cloud benefit allows a company to avoid predicting exactly how much compute capacity it needs months in advance?

Accepted Answer

Elasticity. Elasticity is the Azure cloud benefit that allows a company to automatically scale compute resources up or down based on real-time demand, eliminating the need to predict capacity months in advance. With Azure Virtual Machine Scale Sets or Azure App Service auto-scale, resources can be added or removed dynamically, ensuring you only pay for what you use. This contrasts with traditional on-premises capacity planning, where over-provisioning or under-provisioning is common.

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Fault tolerance

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Geo-redundancy

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Economies of scale

Question 14

Which of the following is a characteristic of the public cloud deployment model?

Accepted Answer

Infrastructure is owned by the provider and shared among multiple customers. In the public cloud deployment model, the cloud provider owns and manages the physical infrastructure (servers, storage, networking), and that infrastructure is shared among multiple customer organizations (tenants). This multi-tenant architecture is a defining characteristic, enabling economies of scale and on-demand resource allocation. Option C correctly identifies this shared, provider-owned model.

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All hardware is owned and managed by the customer

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Resources are dedicated to a single customer organization

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Computing resources are hosted in the customer's own data center

Question 15

According to Microsoft, which factor does NOT affect the SLA percentage for an Azure service?

Accepted Answer

The number of users concurrently accessing the service. The SLA percentage for an Azure service is determined by factors such as redundancy, fault tolerance, and resource configuration, not by the number of concurrent users. Microsoft's SLAs are based on uptime guarantees tied to architectural choices like availability zones, disk types, and availability sets, while user load is managed through scaling and is not a factor in the SLA calculation.

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Whether resources are deployed across availability zones

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Whether Premium SSD or Standard HDD disks are used for VMs

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Whether a single VM or availability set is used