RANGER GAMEZ

Microsoft Azure Fundamentals (AZ-900) · chapter 4 of 14

Kennel, daycare or pet hotel?

In this chapter Objectives 1.3

  1. IaaS, PaaS and SaaS
  2. Use cases for each service type
  3. Practice questions
  4. Chapter recap

Objective 1.3

IaaS, PaaS and SaaS

Infrastructure as a service (IaaS)

Infrastructure as a service (IaaS) is the most flexible service type and gives you the most control. Microsoft maintains the hardware, network connectivity to the internet, and physical security. You handle everything else: installing, configuring and maintaining the operating system, network configuration, and database and storage configuration. You're essentially renting hardware in a cloud datacenter. An Azure virtual machine (VM) is IaaS.

IaaS, PaaS and SaaS as three columns of stacked layers, from data and users at the top down to hardware at the bottom. Orange blocks are what you manage, blue blocks what Microsoft manages. IaaS: you manage data and users, app code, runtime and the operating system; Microsoft manages virtualization and hardware. PaaS: you manage data and users and your app code; Microsoft manages the runtime, operating system, virtualization and hardware. SaaS: you manage only your data and users; Microsoft runs the app and everything under it. An arrow says that from left to right you manage less. Three example cards follow. IaaS, for example Azure Virtual Machines: rent the computer and run your own operating system. PaaS, for example Azure App Service: bring your code and Azure runs it. SaaS, for example Microsoft 365: just sign in and use the app.
IaaS: you run the OS (Azure Virtual Machines). PaaS: you bring the code (Azure App Service). SaaS: you just use the app (Microsoft 365).

Platform as a service (PaaS)

Platform as a service (PaaS) is the middle ground. Microsoft also maintains the operating systems, middleware, development tools and managed runtimes, so you don't worry about licensing or patching operating systems and databases. You focus on your application code, your data and access controls. It's a complete development environment without the headache of running it. Azure App Service is PaaS.

Software as a service (SaaS)

Software as a service (SaaS) is the most complete service: you rent or use a fully developed application. Email, messaging, financial software and productivity apps are common examples, such as Microsoft 365. SaaS is the least flexible type but the easiest to start using, and it needs the least technical expertise. You mainly manage your data, user access, and the devices that connect.

Gus: So nobody at Pawsome ever patched the email server because...

Sam: ...there isn't one for you to patch. Microsoft runs it. That's SaaS.

The dog-care ladder

Picture Ranger's care while the team travels. IaaS is renting an empty kennel: you bring the bed, the food and the schedule. PaaS is doggy daycare: the building, staff and routine are theirs; you bring Ranger and his instructions. SaaS is a full pet-hotel package: drop him off, they do everything, and you only say who may pick him up.

Ranger: looks very interested in the pet-hotel package

Exam tip Control vs effort: IaaS = most control, most work. SaaS = least control, least work. PaaS = in between.

Check yourself 1In which service type is the customer responsible for installing and patching the operating system?

  1. Software as a service (SaaS)
  2. Platform as a service (PaaS)
  3. Infrastructure as a service (IaaS)
  4. None; Microsoft always patches it
Show the answer

Answer: C. Infrastructure as a service (IaaS)

In IaaS you rent the infrastructure and manage everything on it, including installing, configuring and patching the operating system.

Objective 1.3

Use cases for each service type

When IaaS fits

Choose IaaS when you need control, or need to move things as they are:

  • Lift-and-shift migration: set up cloud resources like your on-premises datacenter, then move workloads over with little or no change
  • Testing and development: quickly copy known configurations, start and stop environments, and keep complete control
  • Software that needs a specific operating system setup or custom installs

When PaaS fits

Choose PaaS when developers want to build, not babysit servers:

  • Development framework: build or customize cloud apps from built-in software components, with scalability, high availability and multitenant capability included
  • Analytics or business intelligence: tools as a service to analyze and mine data, find insights and patterns, and predict outcomes

When SaaS fits

Choose SaaS when people just need the finished application:

  • Email and messaging
  • Business productivity applications
  • Finance and expense tracking

Gus: So the store schedule could have been a SaaS app instead of a spreadsheet on the inventory VM?

Sam: Yes. Please. Today.

Exam tip Shortcut: "move existing servers without changes" = IaaS. "Developers focus only on code" = PaaS. "Staff just need email" = SaaS.

Check yourself 2Kibble & Co. wants to move Pawsome Pets' existing inventory server into Azure quickly, with as few changes to it as possible. Which service type fits best?

  1. Software as a service (SaaS)
  2. Platform as a service (PaaS)
  3. Serverless functions
  4. Infrastructure as a service (IaaS)
Show the answer

Answer: D. Infrastructure as a service (IaaS)

Lift-and-shift migration is the classic IaaS use case: rebuild the server as a cloud VM and move the workload with little or no change.

Check yourself 3Pawsome's web developer wants to deploy her code without managing operating systems, patches or servers, while staying in control of the app itself. Which service type fits?

  1. Platform as a service (PaaS)
  2. Infrastructure as a service (IaaS)
  3. Software as a service (SaaS)
  4. A private cloud
Show the answer

Answer: A. Platform as a service (PaaS)

PaaS gives developers a ready platform (OS, middleware, runtime managed by Microsoft) while they keep control of their own application and data.

Practice questions

Answer in your head, then open the answer. Ranger's Sky Desk has 482 questions like these for Azure Fundamentals, with mock exams.

Question 1Pawsome Pets runs its order system on Azure virtual machines (IaaS). Which part does Microsoft maintain?

  1. The guest operating system and all of its security updates
  2. Database and storage configuration
  3. Network configuration of the VMs
  4. Hardware, internet connectivity and physical security
Show the answer

Answer: D. Hardware, internet connectivity and physical security

In IaaS the provider maintains the hardware, network connectivity to the internet and physical security. Everything above that is the customer's.

Question 2Sam wants to run software he installs and manages himself on an operating system he controls. Which Azure offering is an example of IaaS?

  1. Azure App Service
  2. Microsoft 365
  3. Azure Virtual Machines
  4. Azure SQL Database
Show the answer

Answer: C. Azure Virtual Machines

Azure Virtual Machines is IaaS: you manage the OS and everything you install, while Microsoft runs the physical infrastructure.

Question 3Kibble & Co. wants to move an old app to Azure quickly, recreating its servers as they are today and changing as little as possible. Which service type fits, and what is this approach called?

  1. SaaS, as a lift-and-shift migration
  2. IaaS, as a lift-and-shift migration
  3. PaaS, as a rebuild on managed services
  4. IaaS, as a rewrite into serverless functions
Show the answer

Answer: B. IaaS, as a lift-and-shift migration

Lift-and-shift sets up cloud resources similar to the on-premises datacenter and moves the workloads onto IaaS with minimal change.

Question 4Mr. Barkley asks for the simplest way to think about IaaS. Which description is most accurate?

  1. Renting hardware in a cloud datacenter and choosing what runs on it
  2. Renting a finished app that staff just sign in to
  3. Renting a managed runtime that runs only your code
  4. Buying servers that the provider then installs and runs in your building
Show the answer

Answer: A. Renting hardware in a cloud datacenter and choosing what runs on it

With IaaS you are essentially renting hardware in a cloud datacenter; what you do with it is up to you.

Question 5Sam is training a new admin on IaaS. Which statement is true?

  1. The provider applies the customer's OS patches
  2. The customer cannot choose which operating system to run
  3. The customer is responsible for the datacenter's physical security
  4. The customer installs, configures and maintains the operating system
Show the answer

Answer: D. The customer installs, configures and maintains the operating system

IaaS gives the most control and the most responsibility: OS installation, configuration and maintenance, network configuration, and database and storage setup are yours.

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