IaaS, PaaS, SaaS, and shared responsibility
The service type spectrum
The memory aid from the course: IaaS is renting a car, PaaS is hiring a driver, SaaS is taking an Uber.
- IaaS: you manage the OS, apps, network config, and data; Azure manages servers, virtualization, storage, networking. Examples: VMs, VNet, Load Balancer, VPN Gateway.
- PaaS: you manage app code and data; Azure manages the infra, OS, middleware, runtime. Examples: App Service, Azure SQL, Functions, AKS.
- SaaS: you manage user access and data config; Azure manages everything else. Examples: Microsoft 365, Dynamics 365, Power BI.
Pick IaaS for control and legacy apps, PaaS to focus on development, SaaS for ready-to-use software. Scenario questions lean on this constantly.
Shared responsibility
Microsoft always owns the physical datacenters, physical network, and physical hosts.
You always own your data, identities and access, endpoints, and account management, regardless of service type. The middle shifts with the model.
The real-world bite: an open RDP 3389 on your IaaS VM is your problem. A SQL injection hole in your PaaS app is your problem. Unconfigured MFA on SaaS is your problem.