Describe cloud models
📘Microsoft Certified: Azure Fundamentals (AZ-900)
When studying for the AZ-900 exam, it is important to understand the three major cloud deployment models. Deployment models describe where your resources live, who manages them, and who has access to them.
The three cloud models are:
- Public Cloud
- Private Cloud
- Hybrid Cloud
Each model has specific characteristics, benefits, and common use cases. Understanding these will help you answer exam questions correctly.
1. Public Cloud
The public cloud is a cloud environment where computing resources (such as virtual machines, storage, databases, and networking) are owned and operated by a cloud provider like Microsoft Azure.
These resources run in the provider’s data centers, and customers share the platform while each organization’s data and workloads remain isolated.
Key Characteristics (AZ-900 must-know)
- Owned and managed by Microsoft (in Azure’s case).
- Shared physical hardware, but each customer’s environment is secure and separated.
- You pay for what you use (pay-as-you-go model).
- No need to manage or maintain physical hardware.
- High scalability—Azure can allocate more resources instantly.
Benefits
- Cost-effective (no hardware purchase).
- Highly scalable and elastic.
- Maintenance and updates handled by Microsoft.
- Fast deployment of resources.
Typical IT Scenario
A company creates virtual machines, databases, and storage accounts in Azure, letting Microsoft manage the physical servers and networking.
What Azure services fit public cloud?
- Azure Virtual Machines
- Azure Storage
- Azure SQL Database
- Azure App Service
When is public cloud ideal?
- When organizations want to avoid buying and managing hardware.
- When workloads require quick scaling.
- When teams want fast deployments for development and testing.
2. Private Cloud
A private cloud is a cloud environment dedicated to one single organization. The infrastructure is not shared with others and can be hosted:
- On an organization’s own data center, or
- By a third-party provider, but still dedicated to only one customer
Private clouds offer more control and customization, while still using cloud technologies like virtualization and automation.
Key Characteristics
- Used by one organization only.
- More control over security, networking, and compliance.
- Hardware may be on-premises or off-premises, but still private.
- Organization manages many elements, such as:
- hardware
- updates
- software installation
- security controls
Benefits
- Higher level of security and compliance.
- Greater control over infrastructure.
- Customization of systems and policies.
Typical IT Scenario
An organization runs its own virtual machines, storage systems, and applications in its own data center using virtualization technologies (like Hyper-V or VMware), but still applies cloud-style automation.
When is private cloud ideal?
- When strict compliance or legal requirements must be met.
- When organizations need deep customization.
- When workloads can’t be hosted on shared infrastructure.
Azure and private cloud
Although Azure itself is a public cloud, Microsoft supports private cloud technologies like:
- Azure Stack Hub (runs Azure services in your data center)
- Azure VMware Solution (private cloud running VMware, managed by Microsoft)
3. Hybrid Cloud
A hybrid cloud combines public cloud + private cloud. It allows applications and data to operate across both environments while being connected through secure networking.
This model gives organizations flexibility and control.
Key Characteristics
- Mix of on-premises/private cloud + public cloud.
- Connected using:
- VPN
- ExpressRoute
- Secure networking
- Workloads can move between environments.
- Data can stay on-premises while applications run in Azure.
Benefits
- Flexibility — use both environments depending on needs.
- Gradual migration — organizations don’t have to move everything to Azure at once.
- Compliance options — sensitive data stays private, other workloads use public cloud.
- Scalability — overflow workloads can move to Azure (cloud bursting).
Typical IT Scenario
An organization keeps its databases on-premises for compliance but runs web applications in Azure. Both environments work together securely.
When is hybrid cloud ideal?
- When organizations want partial cloud adoption.
- When some systems must stay on-premises.
- When they want to extend or scale their private cloud using Azure.
Azure services that support hybrid cloud
- Azure Arc — manage on-premises and multicloud resources using Azure.
- Azure VPN Gateway — connects on-premises network to Azure.
- Azure ExpressRoute — private dedicated connection to Azure.
- Azure Stack — run Azure services privately.
Comparison Table (Important for AZ-900)
| Feature | Public Cloud | Private Cloud | Hybrid Cloud |
|---|---|---|---|
| Ownership | Cloud provider (e.g., Microsoft) | One organization | Both organization + cloud provider |
| Infrastructure Location | Cloud provider’s data centers | On-premises or dedicated provider | Mix of both |
| Scalability | Very high | Limited by private hardware | High (public cloud can extend capabilities) |
| Cost Model | Pay-as-you-go | Higher cost (hardware + maintenance) | Mix of both |
| Security and Control | Provider-managed | Fully organization-controlled | Mixed |
| Best For | Fast, flexible, cost-effective workloads | High-security, compliance, control | Combination of flexibility + control |
Exam Tips (AZ-900 Focus)
- Public cloud → No hardware to manage, pay-as-you-go, high scalability.
- Private cloud → Single organization, full control, higher cost, custom security.
- Hybrid cloud → Combines both, ideal for gradual cloud adoption and compliance needs.
- Public cloud is not always cheaper, but it reduces capital expenses (CapEx).
- Private cloud typically involves high CapEx but may lower long-term OpEx.
- Hybrid cloud allows cloud bursting, data residency control, and flexibility.
Short Summary
- Public Cloud → Azure-managed environment shared across customers but securely isolated.
- Private Cloud → Cloud technologies used in an environment dedicated to one organization.
- Hybrid Cloud → Combination of on-premises/private cloud and Azure, connected securely.
