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IaaS, PaaS and SaaS

2 min read Quiz included

Cloud services come in three main types. The difference between them is how much of the stack you manage yourself.

Infrastructure as a Service (IaaS)

The provider gives you the raw building blocks: virtual machines, storage and networking. You manage the operating system, runtime, applications and data.

  • Most control, most responsibility
  • Azure examples: Azure Virtual Machines, Azure Virtual Network, managed disks
  • Use cases: "lift and shift" migration of existing servers, test and development environments, workloads that need full control of the OS

Platform as a Service (PaaS)

The provider manages the infrastructure and the operating system, runtime and middleware. You bring your application and data.

  • Developers focus on code, not servers
  • Azure examples: Azure App Service, Azure SQL Database, Azure Functions
  • Use cases: building web apps and APIs, development frameworks, analytics

Software as a Service (SaaS)

The provider runs a complete application. You simply use it, usually through a browser, and manage only your data, users and settings.

  • Least control, least responsibility
  • Examples: Microsoft 365 (Outlook, Teams), Dynamics 365
  • Use cases: email, collaboration, customer relationship management

Who manages what

On-premisesIaaSPaaSSaaSApplicationsYouYouYouProviderDataYouYouYouYouRuntime and middlewareYouYouProviderProviderOperating systemYouYouProviderProviderVirtualisationYouProviderProviderProviderServersYouProviderProviderProviderStorageYouProviderProviderProviderNetworkingYouProviderProviderProviderYou manageThe provider manages
IaaS hands over the hardware, PaaS the operating system and runtime too, SaaS the whole application. Your data stays yours.

Spot the type

The exam names a product and asks which type it is. These are the ones it uses most:

ProductTypeWhat you look after
Azure Virtual MachinesIaaSthe operating system, its updates, everything installed on it
Virtual Machine Scale SetsIaaSthe same, for a group of identical VMs that grows and shrinks
Azure App ServicePaaSyour web app's code and settings
Azure FunctionsPaaS (serverless)the code that runs when an event fires
Azure SQL DatabasePaaSyour tables, data and who can read them
Microsoft 365SaaSyour users, their data and settings
Dynamics 365SaaSyour customer records and business settings
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