Quick definition
IaaS (Infrastructure as a Service) is a cloud computing model that provides virtualized computing resources—such as servers, storage, and networking—over the internet. Instead of buying and maintaining physical hardware, organizations rent infrastructure from a cloud provider and manage operating systems, middleware, and applications themselves.
Core components of IaaS
IaaS typically includes:
- Compute: Virtual machines (VMs), containers, or bare-metal servers.
- Storage: Block, object, and file storage options for persistent data.
- Networking: Virtual networks, load balancers, VPNs, and IP management.
- Virtualization: Hypervisors and orchestration layers that abstract physical hardware.
How IaaS works
Cloud providers maintain physical data centers and expose APIs/management consoles so customers can provision and control virtual resources. Users configure OS, runtime, middleware, and apps while the provider handles the underlying hardware, power, cooling, and basic infrastructure maintenance.
Benefits of IaaS
- Scalability: Rapid provisioning and scaling of resources on demand.
- Cost efficiency: Pay-as-you-go pricing removes large capital expenditures on hardware.
- Flexibility: Wide choice of OS, middleware, and custom configurations.
- Disaster recovery & redundancy: Built-in options for backups, snapshots, and geo-replication.
Common use-cases
Businesses use IaaS for:
- Hosting development and test environments.
- Running scalable web applications and microservices.
- Big data processing and analytics workloads.
- Backup, recovery, and archival storage.
IaaS vs PaaS vs SaaS (short comparison)
IaaS: Provider manages infrastructure. Customer controls OS and applications.
PaaS: Provider manages infrastructure and runtime. Customer deploys applications without managing OS.
SaaS: Provider delivers fully managed applications. Customer uses the software with minimal configuration.
Example providers
Major IaaS providers include Amazon Web Services (EC2, EBS, VPC), Microsoft Azure (Virtual Machines, Managed Disks, Virtual Network), Google Cloud Platform (Compute Engine, Persistent Disk, VPC), and others.
Security and operational considerations
- Shared responsibility: Providers secure the physical infrastructure; customers secure OS, apps, and data.
- Patch management: Customers must keep OS and installed software up to date.
- Network security: Configure firewalls, security groups, and NSGs properly.
- Cost governance: Monitor usage, set budgets and autoscaling policies to avoid surprises.
Short interview-ready answer (30 seconds)
IaaS, or Infrastructure as a Service, is a cloud model that provides virtualized compute, storage, and networking resources over the internet. Customers rent these resources from a provider and manage the operating system and applications, while the provider manages the underlying hardware and data center operations.
Longer interview answer (90 seconds)
IaaS delivers foundational cloud resources—VMs, storage, and virtual networks—on demand through APIs or a console. It removes the need to buy physical servers while giving full control over the software stack, making it ideal for lift-and-shift migrations, development/test environments, and variable workloads. You’re responsible for OS, middleware and apps, and the provider is responsible for physical infrastructure, networking, and virtualization. Key advantages are cost savings, elasticity, and operational speed, while considerations include proper security configuration, patching, and cost management.
Quick example CLI (provision a VM)
# Example (AWS CLI): create a t3.micro EC2 instance
aws ec2 run-instances \
--image-id ami-0abcdefgh12345678 \
--instance-type t3.micro \
--key-name my-keypair \
--security-group-ids sg-0123456789abcdef0 \
--subnet-id subnet-01234567
Whether you’re preparing for interviews or planning cloud migrations, understanding IaaS fundamentals helps you choose the right cloud model and make informed architecture decisions.