Describe cloud service types
📘Microsoft Certified: Azure Fundamentals (AZ-900)
1. What is Infrastructure as a Service (IaaS)?
Infrastructure as a Service (IaaS) is a cloud service model where the cloud provider (like Microsoft Azure) provides the basic IT infrastructure over the internet.
This infrastructure includes:
- Virtual machines (servers)
- Storage
- Networking
- Load balancers
- Firewalls
Instead of buying and maintaining physical servers in a data center, you rent these resources from Azure and manage them through a web portal or command-line tools.
In simple words:
IaaS = Rent virtual servers and networking from the cloud, and manage them yourself.
2. How IaaS Works
In a traditional on-premises environment:
- You buy physical servers.
- You install operating systems.
- You configure networking.
- You manage storage.
- You handle maintenance and hardware failures.
In IaaS:
- Azure manages the physical hardware.
- Azure manages the data center.
- Azure manages power, cooling, and physical security.
- You manage the virtual server (VM), operating system, and applications.
3. Shared Responsibility Model in IaaS
This is very important for the AZ-900 exam.
In IaaS, responsibilities are shared between Azure and the customer.
Azure is responsible for:
- Physical data center
- Physical servers
- Storage hardware
- Networking hardware
- Hypervisor (virtualization layer)
You (the customer) are responsible for:
- Operating system (Windows/Linux)
- Patching the OS
- Applications
- Application data
- Network configuration (inside your virtual network)
- Identity and access management
💡 Key Exam Point:
In IaaS, you manage more compared to PaaS and SaaS.
4. Main Components of IaaS in Azure
For AZ-900, you must understand common Azure IaaS services.
4.1 Azure Virtual Machines (VMs)
- Virtual servers running in Azure.
- You choose:
- Operating system (Windows/Linux)
- CPU size
- Memory
- Storage type
Used for:
- Hosting web servers
- Running business applications
- Running databases
- Testing and development environments
4.2 Azure Virtual Network (VNet)
- Allows Azure resources to communicate securely.
- Similar to a traditional network in a data center.
- Supports:
- Subnets
- IP addresses
- Network security groups (NSGs)
4.3 Azure Storage
Provides different types of storage:
- Blob Storage (for files, backups, media)
- Disk Storage (used by VMs)
- File Storage (shared file systems)
4.4 Load Balancer
Distributes traffic across multiple virtual machines.
Used for:
- High availability
- Preventing overload on one VM
4.5 VPN Gateway
Connects:
- On-premises network to Azure
- Two Azure networks together
Used in hybrid environments.
5. When to Use IaaS
IaaS is best when:
- You need full control over the operating system.
- You are migrating existing applications from on-premises to Azure.
- You need to install custom software.
- You want flexible scaling.
- You want to avoid buying physical servers.
Example in IT environment:
- A company moves its internal Windows Server to Azure VM.
- A development team creates test environments using virtual machines.
- An organization runs a legacy application that requires full OS control.
6. Advantages of IaaS
6.1 No Hardware Management
You don’t buy physical servers.
6.2 Scalability
You can:
- Increase VM size
- Add more VMs
- Remove VMs when not needed
6.3 Pay-As-You-Go Pricing
You pay only for what you use.
6.4 Fast Deployment
You can create a virtual machine in minutes.
6.5 Global Availability
Deploy VMs in different Azure regions worldwide.
7. Disadvantages of IaaS
You still have responsibilities:
- OS patching
- Security configuration
- Application maintenance
- Backup configuration
If you misconfigure something, it can cause:
- Security risks
- Downtime
- Data loss
8. IaaS vs On-Premises
| Feature | On-Premises | IaaS |
|---|---|---|
| Hardware purchase | Required | Not required |
| Maintenance | Customer | Azure handles hardware |
| Scalability | Slow | Fast |
| Initial cost | High | Low |
| OS management | Customer | Customer |
Key Exam Idea:
IaaS reduces hardware responsibility but not OS responsibility.
9. IaaS vs PaaS vs SaaS (Important for Exam)
Understanding the difference is critical for AZ-900.
| Layer | On-Prem | IaaS | PaaS | SaaS |
|---|---|---|---|---|
| Applications | You | You | You | Provider |
| Data | You | You | You | Provider |
| Runtime | You | You | Provider | Provider |
| OS | You | You | Provider | Provider |
| Virtualization | You | Provider | Provider | Provider |
| Servers | You | Provider | Provider | Provider |
| Storage | You | Provider | Provider | Provider |
| Networking | You | Provider | Provider | Provider |
In short:
- IaaS → You manage OS and apps.
- PaaS → You manage apps only.
- SaaS → You just use the software.
10. Exam Tips for IaaS (AZ-900)
You should remember:
- IaaS provides virtualized computing resources.
- Azure manages physical infrastructure.
- Customer manages operating system and applications.
- Azure Virtual Machines are a key example of IaaS.
- IaaS offers the highest level of control among cloud models.
- IaaS requires more management than PaaS and SaaS.
Common exam-style question:
Question: In which cloud model does the customer manage the operating system?
Answer: IaaS.
11. Key Keywords to Remember
- Virtual Machines (VMs)
- Virtual Network (VNet)
- Storage
- Load Balancer
- Shared Responsibility Model
- Scalability
- Pay-as-you-go
- Infrastructure
- Full control over OS
12. Final Summary
Infrastructure as a Service (IaaS) is a cloud service model where:
- Azure provides hardware and virtualization.
- You manage the operating system and applications.
- You get full control over the virtual server.
- You do not manage physical servers.
It is ideal for:
- Migrating existing systems
- Custom server configurations
- Flexible and scalable environments
For AZ-900, always remember:
IaaS = Most control + Most responsibility among cloud service types.
