MS-900 Describe cloud concepts Practice Question
During requirements gathering, an IT manager says the organization must compare service models and identify where the customer manages the most layers. Cloud concept or benefit best matches this requirement?
⚠ Common exam trap
Many exam-takers confuse 'most management' with 'most convenience,' incorrectly selecting PaaS or SaaS because they assume more provider management is the goal, whereas the question explicitly asks for the model where the customer manages the most layers.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Infrastructure as a Service (IaaS)
The IT manager's requirement is to identify the service model where the customer manages the most layers. In Infrastructure as a Service (IaaS), the cloud provider manages only the physical infrastructure (servers, storage, networking), while the customer is responsible for managing the operating system, middleware, runtime, data, and applications. This gives the customer the highest degree of control and management responsibility compared to PaaS or SaaS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Platform as a Service (PaaS)
Why it's wrong here
PaaS sits between IaaS and SaaS: the provider manages the operating system and runtime, so the customer manages fewer layers than with IaaS, not the most. It is tempting because PaaS is a genuine service model, but the stem asks which model leaves the customer managing the most layers.
- ✗
Software as a Service (SaaS)
Why it's wrong here
SaaS leaves the customer managing almost nothing beyond data and access, so it manages the fewest layers, not the most. It is tempting because SaaS is a valid service model, but the stem requires identifying the model with maximum customer-managed layers, which is IaaS.
- ✓
Infrastructure as a Service (IaaS)
Why this is correct
IaaS leaves the customer managing the most layers: operating systems, runtime, middleware, applications and data, while the provider handles virtualisation, servers, storage and networking. This matches the requirement to identify the service model with the greatest customer management responsibility.
- ✗
Hybrid cloud
Why it's wrong here
Hybrid cloud describes a deployment model combining on-premises and cloud infrastructure, not a service model's layer split. It is tempting because hybrid is a legitimate cloud concept, but the stem asks which service model leaves the customer managing the most layers, which is IaaS.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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