MS-900 Describe cloud concepts Practice Question
During a Microsoft 365 planning workshop, host custom applications on virtual machines while managing the operating system. Cloud concept or benefit best matches this requirement?
⚠ Common exam trap
Candidates often confuse PaaS with IaaS because both involve hosting applications, but PaaS does not allow OS-level management, which is the key differentiator in this question.
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, including virtual machines where you can host custom applications and have full control over the operating system. This matches the requirement because IaaS gives you the flexibility to manage the OS, install custom software, and configure the environment without worrying about the underlying physical hardware.
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 abstracts the operating system entirely, so the customer cannot manage the OS as the scenario demands; only IaaS exposes VMs where the customer retains OS control. PaaS is tempting because it hosts custom applications, and it would be correct if the requirement were to deploy code without managing servers.
- ✓
Infrastructure as a Service (IaaS)
Why this is correct
IaaS supplies virtualised compute, storage, and networking where the customer manages the guest operating system and hosts custom applications. This matches the stem's requirement to run custom apps on VMs while retaining OS management responsibility.
- ✗
Hybrid cloud
Why it's wrong here
Hybrid cloud describes combining on-premises and cloud environments, not a service model; it does not specify who manages the operating system on the VMs. It is tempting because the scenario mentions an existing on-premises application, but hybrid connectivity is irrelevant to the hosting model the requirement describes.
- ✗
Software as a Service (SaaS)
Why it's wrong here
SaaS delivers finished applications where the provider manages everything beneath the interface, including the operating system; the requirement explicitly states the customer manages the OS. It is tempting because Microsoft 365 itself is SaaS, but SaaS suits consuming vendor-hosted software, not hosting custom applications on customer-controlled VMs.
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