IaaS vs PaaS vs SaaS Azure Examples: AZ-900 Cloud Models Explained

This guide is for anyone studying for Azure AZ-900 in 2026 who needs to tell IaaS, PaaS, and SaaS apart confidently on exam day.

Definitions of IaaS, PaaS, and SaaS

Cloud computing is delivered in three primary service models. On the AZ-900 exam, you must identify each model from a description and pick the correct Azure example. Here are the plain-English definitions:

Infrastructure as a Service (IaaS)

IaaS provides virtualized compute resources over the internet. You rent VMs, storage, and networks, but you manage the operating system, middleware, runtime, and applications. It offers the most control and the most management overhead.

Platform as a Service (PaaS)

PaaS provides a managed platform for building, testing, and deploying applications. Microsoft manages the infrastructure and platform stack (OS, middleware, runtime). You only bring your code and data. It balances control with convenience.

Software as a Service (SaaS)

SaaS delivers fully managed applications over the internet. You simply use the software. Microsoft handles everything: infrastructure, platform, and application management. You only manage data and user access.

Azure-Specific Examples

IaaS Examples in Azure

• Azure Virtual Machines: Full OS control. You patch, secure, and configure the VM.
• Azure Virtual Machine Scale Sets: Auto-scaling groups of VMs for high availability.
• Azure Dedicated Host: Physical servers dedicated to your organization.

PaaS Examples in Azure

• Azure App Service: Deploy web apps and APIs without managing servers.
• Azure Functions: Event-driven serverless compute. Pay per execution.
• Azure SQL Database: Managed SQL Server with automatic patching and backups.
• Azure Cosmos DB: Globally distributed NoSQL database managed by Microsoft.

SaaS Examples in Azure / Microsoft Cloud

• Microsoft 365: Email, Teams, and Office apps delivered as a service.
• Microsoft Dynamics 365: CRM and ERP applications managed by Microsoft.
• Power BI: Business analytics tool with no infrastructure to manage.

Comparison Table

When to Use Each Model

Service models directly determine who manages what in Azure. For the security implications of each model, see our Azure shared responsibility model guide. For a full study plan, check out our 30-day AZ-900 study guide or the printable cheat sheet.

• Choose IaaS when you need full control over the OS, have legacy apps that require specific environments, or want to replicate an on-premises setup in the cloud.
• Choose PaaS when your team wants to focus on writing code, not managing servers. Ideal for web apps, APIs, microservices, and modern cloud-native development.
• Choose SaaS when you need standard business software immediately without any development, patching, or infrastructure work.

Real Exam Scenarios

AZ-900 does not ask you to recite definitions. It presents scenarios and expects you to select the right model or Azure service. Here are three realistic exam-style situations:

• Scenario 1: "A company wants to host a custom .NET web application without managing virtual machines." Answer: Azure App Service (PaaS).
• Scenario 2: "A team needs to run a legacy Windows Server application that requires a specific registry setting." Answer: Azure Virtual Machines (IaaS).
• Scenario 3: "A startup needs email, file storage, and video conferencing on day one with no IT staff." Answer: Microsoft 365 (SaaS).

For more scenario-based practice, see our guide on how hard AZ-900 really is and what question types to expect.

Frequently Asked Questions