The answer is Infrastructure as a Service (IaaS). This model provides virtualized computing resources over the internet, granting you full control over the operating system and applications while the cloud provider manages the physical hardware. In contrast, PaaS abstracts the OS layer, and SaaS delivers fully managed software, so only IaaS gives you the administrative access to configure and patch the OS yourself. On the Microsoft Azure Fundamentals AZ-900 exam, this distinction tests your understanding of the shared responsibility model, where IaaS shifts hardware management to Azure but leaves OS and app control with you. A common trap is confusing PaaS’s “platform control” with OS control—remember that PaaS manages the runtime, not the OS. For a memory tip, think “IaaS = I Admin the OS and Apps,” while PaaS and SaaS progressively hand over more control to the provider.
AZ-900 Describe cloud concepts Practice Question
This AZ-900 practice question tests your understanding of describe cloud concepts. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A startup wants to avoid managing physical servers and instead focus on developing their application. Which cloud service model provides them with the most control over the operating system and applications while still not managing hardware?
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, giving the startup full control over the operating system, storage, and deployed applications without managing the underlying physical hardware. This model is ideal for a startup that wants to avoid hardware maintenance while retaining the flexibility to configure and manage their own OS and application stack.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Software as a Service (SaaS)
Why it's wrong here
SaaS provides fully managed applications with minimal user control.
✗
Platform as a Service (PaaS)
Why it's wrong here
PaaS abstracts the OS, offering only application-level control.
✓
Infrastructure as a Service (IaaS)
Why this is correct
IaaS gives control over the OS and applications while the provider manages the physical hardware.
Related concept
Read the scenario before looking for a memorised answer.
✗
Functions as a Service (FaaS)
Why it's wrong here
FaaS is for event-driven code execution with no control over the underlying OS.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse PaaS with IaaS, thinking PaaS gives OS control because they can deploy custom code, but PaaS actually abstracts the OS and runtime, whereas IaaS provides full OS access without hardware management.
Detailed technical explanation
How to think about this question
In IaaS, the cloud provider manages the physical hardware, hypervisor, and network infrastructure, while the tenant is responsible for the guest OS, middleware, and applications. This is typically delivered via virtual machines (VMs) using technologies like KVM or Hyper-V, and the tenant can access them through SSH/RDP or APIs. A real-world scenario is a startup running a custom Linux-based application stack on Azure VMs, where they can install specific kernel modules or configure firewall rules without worrying about racking servers.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe cloud concepts — This question tests Describe cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Infrastructure as a Service (IaaS) — Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, giving the startup full control over the operating system, storage, and deployed applications without managing the underlying physical hardware. This model is ideal for a startup that wants to avoid hardware maintenance while retaining the flexibility to configure and manage their own OS and application stack.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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