Describe cloud concepts
Cloud Service Types
CoreChoose IaaS, PaaS, or SaaS from customer control and management responsibility.
Aligned to the AZ-900 skills measured as of July 20, 2026; product behavior verified August 23, 2026.
Why this matters
Service-type decisions show how much of the stack the customer wants to control and whether the desired outcome is infrastructure, an application platform, or a finished application.
Must Know
- IaaS supplies virtualized infrastructure. The provider manages physical facilities and hosts; the customer manages guest operating systems, applications, and data.
- PaaS supplies a managed application platform. The provider manages infrastructure and the platform foundation while the customer deploys application code and manages its data.
- SaaS supplies a complete provider-operated application. The customer configures use, identities, access, and data within the application.
- Choose IaaS for guest-OS or deep software control, PaaS to focus on application development, and SaaS to consume a finished business capability.
- Cloud model (public/private/hybrid) and service type (IaaS/PaaS/SaaS) answer different questions.
Compare and Distinguish
- IaaS vs PaaS: customer-managed guest environment versus provider-managed platform.
- PaaS vs SaaS: deploy your own application versus consume the provider’s completed application.
- IaaS vs on-premises: both can offer deep control, but the cloud provider owns physical IaaS infrastructure.
- Service type vs cloud model: management responsibility versus deployment/ownership relationship.
Scenario examples
- A legacy dependency on a specific guest OS points to IaaS.
- A team that wants to deploy code without patching an OS points to PaaS.
- Employees who need a ready-to-use email application consume SaaS.
Exam traps
- A browser interface alone does not prove a service is SaaS.
- PaaS is not simply a smaller VM.
- SaaS customers still govern their users, access, and data.
Key takeaways
- More customer control generally means more customer management.
- Select by responsibility and outcome, not the product name.
- IaaS, PaaS, and SaaS can coexist in one solution.
Ready for the quiz?
- Which type retains guest-OS control?
- Which type lets developers focus on their code?
- Which type provides a finished application?
Related objectives
- D1.3.S1 — Describe infrastructure as a service (IaaS)
- D1.3.S2 — Describe platform as a service (PaaS)
- D1.3.S3 — Describe software as a service (SaaS)
- D1.3.S4 — Identify appropriate use cases for each cloud service type (IaaS, PaaS, and SaaS)