Azure Functions is the correct choice because it is a serverless compute service designed to execute code in response to events, such as HTTP requests, without requiring you to provision or manage any underlying infrastructure. This makes it ideal for building a serverless API, as it natively supports HTTP triggers that allow you to create RESTful endpoints that scale automatically based on demand. On the Microsoft Azure Fundamentals AZ-900 exam, this question tests your understanding of core serverless compute options, often contrasting Azure Functions with Azure Logic Apps (which is more workflow-oriented) or Azure App Service (which requires managing a hosting plan). A common trap is choosing App Service because it can also handle HTTP requests, but remember that App Service is not serverless—it runs on dedicated or reserved instances. For a quick memory tip: think of Azure Functions as “code on demand” that fires only when an HTTP request hits it, just like a vending machine that only works when you press a button.
AZ-900 Describe Azure architecture and services Practice Question
This AZ-900 practice question tests your understanding of describe azure architecture and services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 developer needs to create a serverless API that executes code in response to HTTP requests without managing any server infrastructure. Which Azure service is BEST suited?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Functions
Azure Functions is the correct choice because it is a serverless compute service that allows you to run event-driven code without provisioning or managing infrastructure. It natively supports HTTP triggers, enabling the creation of RESTful APIs that execute code in response to HTTP requests, and scales automatically based on demand.
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.
✗
Azure App Service
Why it's wrong here
App Service hosts web apps and APIs but requires choosing and managing an App Service Plan (server tier).
✓
Azure Functions
Why this is correct
Azure Functions is serverless — HTTP-triggered functions execute code on demand with no infrastructure management.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Kubernetes Service
Why it's wrong here
AKS requires managing a Kubernetes cluster, which is substantial infrastructure overhead.
✗
Azure Virtual Machines
Why it's wrong here
VMs require the most infrastructure management — OS, patching, scaling all fall to the customer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Azure App Service (PaaS) with serverless, but App Service still requires managing an app service plan and does not provide the same granular, event-driven scaling and pay-per-execution model as Azure Functions.
Detailed technical explanation
How to think about this question
Azure Functions uses a consumption plan where execution is billed only for the time your code runs, with automatic scaling from zero to thousands of instances based on incoming HTTP requests. Under the hood, HTTP triggers bind to a webhook endpoint, and the Functions runtime handles request routing, authentication, and response serialization via the Azure WebJobs SDK. A real-world scenario is building a lightweight microservice for processing form submissions without worrying about server maintenance or idle costs.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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 Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Functions — Azure Functions is the correct choice because it is a serverless compute service that allows you to run event-driven code without provisioning or managing infrastructure. It natively supports HTTP triggers, enabling the creation of RESTful APIs that execute code in response to HTTP requests, and scales automatically based on demand.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is developing a REST API that processes incoming HTTP requests. The API usage is highly unpredictable; sometimes it receives thousands of requests per minute, and at other times it receives zero requests for hours. The company wants to pay only for the compute time consumed when the API code is actually executing. They also want Microsoft to automatically handle scaling and maintenance of the underlying server infrastructure. Which Azure compute service should the company use?
medium
✓ A.Azure Functions (Consumption plan)
B.Azure App Service (Basic tier)
C.Azure Container Instances
D.Azure Logic Apps
Why A: Azure Functions with the Consumption plan is the correct choice because it is a serverless compute service that executes code only when triggered by incoming HTTP requests, automatically scaling to handle unpredictable workloads. The Consumption plan charges only for the compute time consumed during execution, with no cost when the function is idle, and Microsoft fully manages the underlying infrastructure, including scaling and maintenance.
Last reviewed: Jun 11, 2026
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