IaaS
IaaS (Infrastructure as a Service) is a cloud computing model that delivers IT infrastructure — virtual servers, storage, networking, and security — as an on-demand, pay-per-use service. Examples: AWS EC2, Microsoft Azure Virtual Machines, Google Compute Engine.
What Is IaaS?
IaaS (Infrastructure as a Service) is a cloud computing model that delivers IT infrastructure — virtual servers, storage, networking, and security — as an on-demand, pay-per-use service. Instead of purchasing and operating physical hardware, organisations rent infrastructure from cloud providers like AWS, Microsoft Azure, Google Cloud Platform, or Oracle Cloud, and manage their own operating systems, applications, and data on top.
IaaS is one of the three primary cloud delivery models alongside PaaS (Platform as a Service) and SaaS (Software as a Service). It offers the most control and flexibility of the three, making it the natural starting point for cloud migrations, lift-and-shift workloads, and custom platforms.
IaaS Definition
IaaS (Infrastructure as a Service) is a cloud computing model where the provider supplies fundamental computing resources — virtualised compute, storage, and networking — over the internet, billed by usage. The customer brings their own operating system, applications, and data and manages them on top of the provider’s infrastructure.
Examples of IaaS services: Amazon EC2, AWS S3, Azure Virtual Machines, Google Compute Engine, Oracle Cloud Compute, IBM Cloud Virtual Servers.
How Does IaaS Work?
The provider operates physical data centres globally, virtualises compute and storage resources, and exposes them through APIs and web consoles. Customers can:
- Provision a virtual machine in 30–120 seconds via API or CLI.
- Attach block storage volumes that resize on demand.
- Define virtual networks (VPCs) with subnets, security groups, and routing.
- Scale instances up/down automatically based on load (autoscaling).
- Pay per second, hour, or month — no long-term commitments required.
Most IaaS deployments are now driven by Infrastructure as Code (Terraform, Pulumi, AWS CloudFormation, Azure Bicep), which lets teams version-control and replicate environments.
IaaS vs PaaS vs SaaS — the Cloud Pyramid
| Layer | Provider manages | Customer manages | Example |
|---|---|---|---|
| IaaS | Hardware, virtualisation, networking | OS, runtime, apps, data, identity | AWS EC2, Azure VM, GCE |
| PaaS | + OS, runtime, scaling | Apps, data | Heroku, Elastic Beanstalk, App Engine |
| SaaS | Everything | Configuration, data input | Microsoft 365, Salesforce |
More abstraction = less work but less control. Most enterprises use all three — IaaS for regulated/legacy workloads, PaaS for new applications, SaaS for commodity functions like email, CRM, and collaboration.
What IaaS Includes
A typical IaaS catalogue covers six core resource types:
- Compute — virtual machines, GPU instances, bare-metal servers, autoscaling groups, container infrastructure (managed Kubernetes).
- Storage — block storage attached to VMs, object storage for files and backups, file storage for shared volumes, archival storage for cold data.
- Networking — virtual private clouds (VPC/VNet), subnets, security groups, load balancers, VPN gateways, peering, content delivery networks (CDN).
- Identity and Access — IAM roles and policies, encryption key management (KMS), federated identity.
- Monitoring and Logging — metrics, logs, traces, alerting, dashboards.
- Security — DDoS protection, network firewalls, web application firewalls (WAF), threat detection.
Benefits of IaaS
- Cost flexibility — OpEx replaces CapEx; no upfront hardware investment; pay only for what you use.
- Elasticity — scale up or down in minutes, autoscaling reacts to demand peaks.
- Speed of provisioning — a new server in 30 seconds vs weeks for physical hardware procurement.
- Global reach — deploy in dozens of regions and hundreds of availability zones worldwide.
- Reliability — high availability with multi-AZ designs, providers offer 99.99% SLAs.
- Focus on outcomes — engineering teams stop racking servers and patching firmware and focus on applications.
Challenges and Risks
- Cost surprises — without active FinOps and right-sizing, cloud bills can exceed on-prem alternatives 2–3×.
- Security responsibility — Shared Responsibility Model means most cloud breaches come from customer misconfigurations.
- Vendor lock-in — proprietary services accelerate delivery but raise the cost of leaving.
- Skill gap — cloud-native operations require Terraform, Kubernetes, FinOps, and SRE skills the team may not have.
- Egress fees — data transferred out of the cloud is expensive ($0.05–$0.12/GB), can trap data in the provider.
IaaS Security — the Shared Responsibility Model
IaaS uses a clear split:
- Provider secures — physical security, networking hardware, hypervisor, host operating system, the cloud platform itself.
- Customer secures — guest operating system patching, application code, data, identity and access policies, network controls (security groups, firewalls), encryption keys, audit and logging configuration.
Most cloud breaches in the last decade — from Capital One (2019) to T-Mobile (2023) — were caused by customer-side misconfigurations, not provider failures. The most common: public S3/Blob buckets, leaked access keys committed to GitHub, over-permissive IAM, missing MFA, unpatched VMs.
Best Practices
- Use Infrastructure as Code (Terraform, Pulumi) — every change versioned, reviewed and reproducible.
- Apply least-privilege IAM with short-lived credentials and federated identity (SSO).
- Enforce MFA on every privileged account, including service accounts.
- Enable provider-native security (AWS Config + GuardDuty, Azure Defender, GCP Security Command Center) from day one.
- Adopt CIS benchmarks and policy-as-code (OPA, AWS Config Rules) to detect misconfigurations automatically.
- Implement continuous cost monitoring (FinOps) — budgets, anomaly detection, automated right-sizing.
- Plan for disaster recovery — multi-region, immutable backups, regular DR tests.
Related Terms
Explore Our Services
Need help designing, securing or auditing IaaS environments?
- Cloud security audit — assess your cloud security posture
- Penetration testing — verify cloud and hybrid environments
- SOC as a Service — 24/7 monitoring across cloud and on-premises
Frequently asked questions
+ What is IaaS in simple terms?
IaaS (Infrastructure as a Service) is the cloud model where you rent IT infrastructure — virtual servers, storage, networks — over the internet on a pay-per-use basis, rather than buying and operating your own hardware. The provider (AWS, Microsoft Azure, Google Cloud, Oracle Cloud) manages the physical data centres, hardware, virtualisation, and the lowest network layer. You manage the operating system, applications, data, and identity. IaaS gives the most control of any cloud model and is best for migrating existing applications, building custom platforms, or running workloads that need fine-grained tuning.
+ What is the difference between IaaS, PaaS and SaaS?
Three cloud delivery models with different management splits: (1) IaaS — provider manages hardware, virtualisation; customer manages OS, runtime, apps, data (examples: AWS EC2, Azure VM), (2) PaaS (Platform as a Service) — provider also manages OS and runtime; customer manages apps and data (examples: Heroku, AWS Elastic Beanstalk, Azure App Service, Google App Engine), (3) SaaS (Software as a Service) — provider manages everything; customer just uses the application (examples: Microsoft 365, Salesforce, Gmail). Trade-off: more abstraction = less work, less control, harder to migrate away.
+ What are examples of IaaS providers?
Five major IaaS providers as of 2026: (1) Amazon Web Services (AWS) — EC2 (virtual machines), EBS (block storage), VPC (networking), the market leader, (2) Microsoft Azure — Virtual Machines, Managed Disks, Virtual Network, strongest in enterprise/Microsoft ecosystem, (3) Google Cloud Platform — Compute Engine, Persistent Disk, VPC, leader in data/AI workloads, (4) Oracle Cloud Infrastructure (OCI) — strong in high-performance compute and Oracle DB workloads, (5) IBM Cloud — focus on hybrid and regulated industries. Smaller players include DigitalOcean, Linode (Akamai), Vultr, Hetzner — competitive pricing for smaller workloads.
+ What does IaaS include?
Six core components: (1) Compute — virtual machines (VMs), bare-metal servers, GPU instances, autoscaling groups, (2) Storage — block storage attached to VMs (EBS, Managed Disks), object storage (S3, Blob, GCS), file storage (EFS, Azure Files), (3) Networking — virtual private clouds (VPC/VNet), subnets, security groups, load balancers, VPN, peering, (4) Identity & Access — IAM roles and policies, key management (KMS), (5) Monitoring & Logging — CloudWatch, Azure Monitor, Cloud Logging, (6) Security — DDoS protection, network firewalls, WAFs, threat detection (GuardDuty, Defender for Cloud).
+ What are the benefits of IaaS?
Six benefits: (1) Cost flexibility — OpEx instead of CapEx, no upfront hardware investment, pay only for what you use, (2) Elasticity — scale up or down in minutes (autoscaling), (3) Speed — provision a server in 30 seconds vs weeks for physical hardware, (4) Global reach — deploy in 30+ regions and 100+ availability zones worldwide, (5) Reliability — high availability, multi-AZ deployments, providers offer 99.99% SLAs, (6) Focus — engineering teams stop racking servers and focus on applications. Trade-off: long-running stable workloads can be cheaper on-prem; cloud bills surprise organisations without active FinOps.
+ What are the security considerations for IaaS?
IaaS uses the Shared Responsibility Model: provider secures the cloud (hardware, hypervisor, physical security); customer secures *what runs in* the cloud (OS patching, configurations, IAM, application code, data). Common customer mistakes that cause breaches: (1) public-facing storage buckets (S3, Blob), (2) leaked access keys committed to GitHub, (3) over-permissive IAM and lack of MFA, (4) unpatched VMs exposed to the internet, (5) missing encryption at rest, (6) lack of logging/monitoring. Best practices: enable provider-native security tools (AWS Config, Azure Defender, Security Command Center), enforce least privilege, use Infrastructure as Code (Terraform) with policy-as-code (OPA, CIS Benchmarks).
+ When should you use IaaS instead of PaaS or SaaS?
Choose IaaS when you need: (1) full control of OS and runtime (custom kernels, low-level tuning, specific compliance requirements), (2) lift-and-shift migration of existing applications without refactoring, (3) workloads using software unsupported by PaaS (e.g. legacy databases, custom middleware), (4) infrastructure for proprietary platforms (e.g. building your own internal PaaS or running self-hosted Kubernetes). Choose PaaS for new applications when you want to skip OS management; choose SaaS when a vendor solution covers the use case (CRM, email, collaboration). Most enterprises use a mix — IaaS for legacy/regulated, PaaS for new apps, SaaS for commodity functions.