Describe cloud service types
📘Microsoft Certified: Azure Fundamentals (AZ-900)
In cloud computing, there are three main service types:
- IaaS (Infrastructure as a Service)
- PaaS (Platform as a Service)
- SaaS (Software as a Service)
Each has its own strengths, responsibilities, and best use cases. Let’s go through them one by one.
1️⃣ Infrastructure as a Service (IaaS)
Definition:
IaaS provides virtualized computing resources over the internet. With IaaS, you get the basic building blocks of IT—virtual machines, storage, and networks—without buying or managing physical hardware. You manage operating systems, applications, and data, while the cloud provider handles hardware, storage, networking, and virtualization.
Key responsibilities in IaaS:
| Component | Responsibility |
|---|---|
| Hardware (servers, storage, network) | Managed by cloud provider |
| Virtual machines & OS | Managed by customer |
| Applications & data | Managed by customer |
| Middleware, runtime, security patches | Managed by customer |
When to use IaaS (Use Cases):
- Temporary or test environments:
- You can quickly spin up VMs for development, testing, or experiments without buying hardware.
- Extending on-premises data centers:
- Companies can expand their existing IT infrastructure to the cloud for more capacity or backup.
- Running custom applications:
- Applications that require control over OS or specific configurations.
- Disaster recovery and backup solutions:
- Quickly replicate servers and storage in the cloud to protect against failures.
Example in IT environment:
- A company runs a web application that needs Windows Server and SQL Server. Using IaaS, they create virtual machines in Azure with Windows and SQL pre-installed, manage updates, and deploy their application.
2️⃣ Platform as a Service (PaaS)
Definition:
PaaS provides a ready-to-use platform for developing, testing, and deploying applications. The cloud provider manages hardware, operating systems, networking, storage, and runtime. You focus only on your applications and data.
Key responsibilities in PaaS:
| Component | Responsibility |
|---|---|
| Hardware, OS, runtime, middleware | Managed by cloud provider |
| Applications & data | Managed by customer |
When to use PaaS (Use Cases):
- Application development and deployment:
- Developers can build apps quickly without worrying about servers, OS, or infrastructure.
- Web applications and APIs:
- PaaS provides built-in services like authentication, databases, and messaging.
- Scaling applications automatically:
- PaaS handles scaling based on demand without manual intervention.
- Integrating with other services:
- Easy to connect to databases, AI services, or analytics tools.
Example in IT environment:
- A software team builds a new web application in Azure App Service. They just write the code and deploy it. Azure manages the servers, OS updates, and scaling automatically.
3️⃣ Software as a Service (SaaS)
Definition:
SaaS delivers fully functional applications over the internet. Users don’t manage hardware, OS, or platforms—they just use the software through a browser or app. The cloud provider handles everything.
Key responsibilities in SaaS:
| Component | Responsibility |
|---|---|
| Application | Managed by cloud provider |
| Data storage, runtime, OS, hardware | Managed by cloud provider |
| Security & updates | Managed by cloud provider |
When to use SaaS (Use Cases):
- Business productivity software:
- Email, calendars, collaboration tools—no installation or maintenance required.
- Customer relationship management (CRM):
- SaaS CRM platforms are ready-to-use for managing sales and customer data.
- Enterprise resource planning (ERP):
- Companies can use SaaS ERP software to manage finances, HR, and operations.
- Rapid deployment and accessibility:
- Users can access SaaS apps from any device with internet.
Example in IT environment:
- Employees use Microsoft 365 for email, Teams for collaboration, and SharePoint for file storage. All updates, security, and server management are handled by Microsoft.
4️⃣ Quick Comparison of Use Cases
| Service Type | Managed by Provider | Managed by You | Ideal Use Cases |
|---|---|---|---|
| IaaS | Hardware, network | OS, apps, data | Custom apps, test environments, DR, extending data centers |
| PaaS | Hardware, OS, runtime | Apps, data | App development, web apps, APIs, automated scaling |
| SaaS | Everything | Just use the app | Email, CRM, ERP, collaboration tools |
Key Exam Tips:
- Remember the responsibilities:
- IaaS → you manage most.
- PaaS → you manage apps/data only.
- SaaS → you just use it.
- Focus on scenarios:
- The exam often asks which service type is best for development, testing, or productivity tools. Think in terms of control vs convenience.
- Don’t confuse scaling:
- IaaS can scale, but you manage it.
- PaaS and SaaS often scale automatically.
✅ Summary:
- IaaS → Virtual machines, storage, networking. You control everything else.
- PaaS → Pre-configured platform for app development. Focus on code and data.
- SaaS → Ready-to-use software. Just use it—provider handles everything.
Understanding these use cases is crucial for the AZ-900 exam because questions often describe a scenario and ask which cloud service type is appropriate.
