AZ-900 — Example Quiz

Consumption-based pricing means you pay for what you use — no upfront hardware costs. This is one of the fundamental economic benefits of cloud computing. Elasticity is about scaling resources up and down, which is related but distinct.

A hybrid cloud combines on-premises infrastructure (or a private cloud) with public cloud services. This lets organisations keep sensitive workloads local while leveraging the scalability of the public cloud for everything else.

With PaaS (e.g. Azure App Service), the provider manages the OS, runtime, and infrastructure. You just deploy your application code. VM patching, network infrastructure, and hardware are all the provider's responsibility — those are IaaS or on-premises concerns.

SaaS provides a complete application (e.g. Microsoft 365, Salesforce). The provider manages everything — infrastructure, platform, OS, and the application itself. The customer only manages their data and user access.

Elasticity is the ability to automatically scale resources to match demand — scaling out when traffic spikes and scaling back in when it drops. High availability keeps systems running; agility is about rapid deployment; geo-distribution spreads resources across regions.

An entire data centre failure requires geographic redundancy. Deploying across multiple Azure regions ensures the application survives a regional outage. Availability sets and single-region load balancing protect against failures within a data centre, not across data centres.

Cloud computing offers rapid scalability (provision in minutes, not weeks) and shifts hardware costs from capital expenditure to operational expenditure. It does not provide unlimited bandwidth (you pay for egress), does not eliminate security responsibilities (shared responsibility model), and does not guarantee zero downtime (SLAs offer targets, not absolutes).

The shared responsibility model defines which security tasks the provider handles and which the customer handles. The split varies by service type: with IaaS the customer manages more (OS, apps, data); with SaaS the provider manages most of the stack. The customer is always responsible for their data and access management.

Purchasing physical hardware is a capital expenditure — a large upfront investment in assets that depreciate over time. Cloud computing shifts this to operational expenditure (OpEx), where you pay ongoing costs based on usage.

An Azure region is a geographical area containing one or more data centres networked together with low-latency connections. When you deploy a resource to a region, Azure places it in one of these data centres.

Availability Zones are physically separate data centres within a single Azure region. Each zone has independent power, cooling, and networking. Deploying across zones protects against single data centre failures within that region.

Azure SQL Database is a PaaS offering — Microsoft manages the VM, OS, patching, and backups. You focus on your database and queries. Running SQL Server on a VM (IaaS) means you manage the OS and patching yourself. Blob Storage is for unstructured data, not relational databases.

Regions (geographic locations), resource groups (logical containers for resources), and subscriptions (billing and access boundaries) are core architectural components in Azure. Pricing tiers and SLAs are commercial constructs, not architectural ones.

Separate subscriptions provide clear billing boundaries — each subscription generates its own invoice and can have its own payment method. Resource groups can be tagged for cost tracking, but subscriptions provide the cleanest separation for independent billing. Tags can supplement this but are not a billing boundary on their own.

Azure Advisor analyses your resource configuration and usage, then provides personalised best-practice recommendations across five categories: reliability, security, performance, cost, and operational excellence. Monitor collects metrics and logs; Service Health tracks Azure outages; Policy enforces rules.

A resource group is a logical container — it has a location (for metadata storage), but the resources inside it can be in any Azure region. You might have a resource group in UK South containing a VM in East US and a database in West Europe.

The hierarchy from broadest to narrowest is: Management group (can contain multiple subscriptions) → Subscription (billing boundary, contains resource groups) → Resource group (logical container for resources) → Resource (individual service instance like a VM or database).

ARM templates (and their successor, Bicep) let you define infrastructure as code in a declarative JSON or Bicep format. Azure deploys and manages the resources to match your template. The CLI and Portal are tools for interacting with Azure, but they are imperative (you tell them what to do step by step). Cloud Shell is a browser-based terminal.

Service endpoints and private endpoints allow you to restrict access to Azure PaaS services (like SQL Database and Blob Storage) so they are only reachable from specific virtual networks or IP addresses. Azure AD handles identity, DDoS Protection mitigates attacks, and Front Door is a global load balancer and CDN.

Azure Functions is a serverless compute service — it runs small pieces of code (functions) in response to triggers like HTTP requests, queue messages, timers, and events. It is not designed for hosting desktop applications, managing identity, or storing files (that's Blob Storage).