What does IaaS stand for?
IaaS stands for Infrastructure as a Service. The cloud model where the provider supplies virtual machines, storage and networking and you install, run and patch the operating systems and software yourself, as with Amazon EC2 or Azure VMs. It gives the most control of the three models but also the most responsibility.
IaaS is the cloud model in which the provider rents out the basic building blocks: virtual machines, storage and networks. The provider runs the data centre, the physical servers and the virtualization layer. The customer chooses and installs the operating system and is responsible for patching it, configuring its firewall, installing applications and protecting the data. It offers the most control of the three cloud service models and leaves the most work with the customer.
IaaS in practice: an example
A company needs a test server for three weeks. Instead of buying hardware, an administrator creates a virtual machine at a cloud provider in ten minutes, installs the software and deletes the machine when testing ends. During those weeks, operating system updates on that machine are the administrator's job, not the provider's.
What IaaS is confused with
IaaS vs PaaS: what is the difference?
With IaaS you manage the operating system and everything on it. With PaaS the provider manages the operating system and runtime, and you bring only your application and data. What PaaS stands for
IaaS vs SaaS: what is the difference?
IaaS gives you virtual hardware to build on. SaaS gives you a finished application to use. What SaaS stands for
Which exams cover IaaS?
IaaS is on the official CompTIA acronym list for two of the four exams covered here.
- Network+ N10-009: 1.0 (Networking Concepts).
- A+ 220-1201 and 220-1202: 220-1201 4.0 (Virtualization and Cloud Computing).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. A company rents virtual machines from a cloud provider and installs its own operating systems and applications on them. Which model is this?
- SaaS
- PaaS
- IaaS
- Colocation of its own hardware
Show the answer
C. IaaS. Renting virtual machines, storage and networks and managing everything from the operating system upward is infrastructure as a service.
2. In an IaaS deployment, who is responsible for patching the guest operating system of a virtual machine?
- The cloud provider
- The customer
- The internet service provider
- Nobody; it is automatic in every case
Show the answer
B. The customer. The provider's responsibility ends at the virtualization layer. The operating system inside the virtual machine belongs to the customer.
Sources: NIST SP 800-145, The NIST Definition of Cloud Computing; NIST glossary: Infrastructure as a Service. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 11 November 2026.