AZ-900 Describe cloud concepts Practice Question
What is 'serverless computing'?
⚠ Common exam trap
A common mix-up: candidates confuse 'serverless' with 'no servers at all' (Option A) or 'no operating system' (Option C), when in reality serverless abstracts server management but still uses servers and OSes under the hood.
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
✓
A model where developers deploy code without managing server infrastructure, paying only for execution
Serverless computing is a cloud execution model where the cloud provider dynamically manages the allocation and provisioning of servers. Developers write and deploy code in the form of functions (e.g., AWS Lambda, Azure Functions) without provisioning or managing any underlying server infrastructure, and they are billed only for the actual compute time consumed during execution, not for idle capacity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Computing that uses no physical servers anywhere in the world
Why it's wrong here
Although the term 'serverless' suggests a complete absence of servers, every cloud function still executes on physical hardware located in provider data centers. The difference is that customers never see or manage those servers—the provider handles capacity, provisioning, and maintenance. Thus, serverless is an operational abstraction, not a literal elimination of physical computing resources.
- ✓
A model where developers deploy code without managing server infrastructure, paying only for execution
Why this is correct
This is the correct definition because serverless computing, such as Azure Functions, lets developers deploy individual functions or code snippets without provisioning or managing virtual machines, operating systems, or clusters. The platform automatically scales from zero to demand, and billing is based solely on the number of executions and the duration of each run, rather than on pre-purchased capacity.
- ✗
Running applications without an operating system
Why it's wrong here
Serverless functions are not running without an operating system; they are packaged into containers that include minimal operating system or runtime resources, such as Linux, even though the developer never interacts with them. The provider runs this OS layer, performs all patches, and isolates each execution. So the abstraction eliminates developer administration, but the underlying OS instances absolutely exist during execution.
- ✗
Hosting applications on shared physical hardware
Why it's wrong here
Hosting applications on shared physical hardware describes the foundational model of virtualization, where multiple virtual machines run on a single server, but that is not what distinguishes serverless. In serverless, even the VM and container orchestration are hidden from the developer; the code executes in an ephemeral runtime managed by the provider. Hardware sharing is a lower-level detail that applies to many services, including IaaS, not a unique trait of serverless.
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 |
Go deeper
Related to this question
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What is Cloud Computing?
Key term
Serverless computing
Serverless computing is a cloud execution model where the cloud provider dynamically manages the allocation and provisioning of servers, allowing developers to write and deploy code without thinking about the underlying infrastructure.
Key term
Serverless
Serverless is a cloud computing model where the cloud provider manages the servers, and you only pay for the actual compute time your code uses, without having to worry about provisioning or maintaining infrastructure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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