MS-900 Describe cloud concepts Practice Question
A company wants to reduce hardware maintenance costs by moving to the cloud. They need to maintain full control over the operating system, applications, and security configurations, but do not want to manage physical servers or data center facilities. Which cloud service model should they choose?
⚠ Common exam trap
A common mix-up: candidates confuse PaaS with IaaS because both are cloud models, but PaaS removes control over the OS and runtime environment, which is the critical distinction when the question explicitly requires maintaining full control over the operating system and security configurations.
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)
Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, allowing the company to deploy and manage their own operating systems, applications, and security configurations while offloading the physical hardware and data center management to the cloud provider. This model gives the highest level of control over the software stack without the burden of maintaining physical servers, aligning perfectly with the requirement to reduce hardware maintenance costs while retaining full administrative access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Software as a Service (SaaS)
Why it's wrong here
Software as a Service (SaaS) delivers fully functional applications accessible via a browser, where the vendor manages the entire stack, including the hardware, operating system, middleware, and application itself. While this eliminates hardware maintenance entirely, it also strips the customer of any control over the OS or security configuration, as users can only configure application-level settings. Therefore, although SaaS reduces maintenance costs, it fails the requirement to maintain OS and security control, making it an incorrect choice.
- ✗
Platform as a Service (PaaS)
Why it's wrong here
Platform as a Service (PaaS) supplies a managed hosting environment for application development and deployment, abstracting away the underlying servers, storage, and operating system. The provider handles patches, updates, and hardware maintenance, but this level of management limits your ability to configure the OS or security settings, since those are fixed by the platform. For organizations that need just a deployment platform, PaaS is valid, but for one requiring explicit OS control alongside reduced hardware costs, PaaS does not satisfy the criterion.
- ✓
Infrastructure as a Service (IaaS)
Why this is correct
Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, with the cloud provider owning and maintaining the physical servers, storage, and networking equipment. This shifts hardware maintenance and capital costs to the provider, while you retain full administrative control over the operating system, runtime, and security configurations. That combination of provider-managed hardware and customer-managed OS precisely matches the requirement to reduce maintenance costs while keeping administrative authority.
- ✗
On-premises
Why it's wrong here
On-premises deployment is not a cloud service model at all; it involves purchasing and hosting all servers, storage, and networking equipment within your own data center. This approach requires your IT staff to handle every hardware repair, rack replacement, and firmware update, so it increases rather than reduces hardware maintenance costs. Because the goal is to move to the cloud to offload hardware maintenance, maintaining on-premises infrastructure directly contradicts the objective, making it the incorrect answer.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MS-900 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MS-900 exam.