AZ-900 - Describe Cloud Concepts (29% of the exam) - Section 1.3

Describe cloud service types and the appropriate use cases for IaaS, PaaS, and SaaS.

Compare Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) by how much of the stack the customer manages versus the provider. Choose the right service type for a scenario, such as a lift-and-shift VM (IaaS), a managed web app (PaaS), or off-the-shelf productivity software (SaaS).

Infrastructure as a ServicePlatform as a ServiceSoftware as a Serviceservice type use casesshared responsibility by service type

Practice question for this objective

Free sampleDescribe Cloud Conceptsmedium

Comparing infrastructure as a service, platform as a service, and software as a service strictly by how much operational responsibility the customer carries, which one places the least operational burden on the customer?

AInfrastructure as a service (IaaS)
BPlatform as a service (PaaS)
CSoftware as a service (SaaS) Correct
DAll three carry equal burden

Operational burden falls from IaaS to PaaS to SaaS, so SaaS places the least responsibility on the customer. Along the control-versus-overhead axis, responsibility falls as you move from IaaS to PaaS to SaaS, so SaaS leaves the provider managing nearly the whole stack while the customer mainly handles its data and access, giving the lowest operational overhead.

Why A is wrong: IaaS leaves the customer responsible for the operating system, networking, and storage configuration, so it carries the largest operational burden of the three rather than the least.

Why B is wrong: PaaS reduces the customer's load by having the provider maintain the OS and tools, but the customer still develops and operates its own application, so it is not the lightest of the three.

Why C is correct: Correct. Along the control-versus-overhead axis, responsibility falls as you move from IaaS to PaaS to SaaS, so SaaS leaves the provider managing nearly the whole stack while the customer mainly handles its data and access, giving the lowest operational overhead.

Why D is wrong: The three models deliberately differ along a control-versus-overhead axis, so claiming equal burden ignores the defining distinction between IaaS, PaaS, and SaaS.

See more AZ-900 practice questions, answers explained.

Exam traps in Describe Cloud Concepts

Answers that look right on this material and are not. Each one is a distractor from a different question in the AZ-900 bank for this domain.

Yes
Why it is wrong: The description fits SaaS instead, where the provider handles most of the stack; mapping that to IaaS reverses the responsibility split.
It is fully the provider's, because the provider owns and operates every layer of the platform service end to end
Why it is wrong: A candidate may assume PaaS means the provider does everything, but identity and access never becomes wholly the provider's job because the customer still defines which users and roles exist.
The physical hosts running in the datacenter
Why it is wrong: Physical hosts are always the provider's responsibility, not the customer's.

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