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Cloud Concepts: Core Principles for AZ-900

Cloud computing delivers IT resources over the internet on a pay-as-you-go basis. Understanding its service models, deployment models, and key benefits is essential for the AZ-900 exam.

2 min read

What is Cloud Computing?

Cloud computing is the delivery of computing services—including servers, storage, databases, networking, software, and analytics—over the internet. Users pay only for what they consume, avoiding large upfront capital expenditures.

Service Models

  • IaaS (Infrastructure as a Service): Provides virtualized computing infrastructure. The customer manages the OS, middleware, and applications. Example: Azure Virtual Machines.
  • PaaS (Platform as a Service): Provides a managed platform for developing and deploying applications. The customer manages only the application and data. Example: Azure App Service.
  • SaaS (Software as a Service): Delivers fully managed software applications over the internet. The provider manages everything. Example: Microsoft 365.

Deployment Models

  • Public Cloud: Resources are owned and operated by a third-party provider and shared across multiple customers.
  • Private Cloud: Resources are used exclusively by a single organization, either on-premises or hosted by a third party.
  • Hybrid Cloud: Combines public and private clouds, allowing data and applications to be shared between them.

Key Benefits of Cloud Computing

  • High Availability: Services are designed to remain accessible with minimal downtime, often backed by SLAs.
  • Scalability: Resources can be scaled up (vertical) or out (horizontal) to meet demand.
  • Elasticity: Resources can automatically expand or shrink based on workload changes.
  • Agility: New resources can be provisioned quickly, accelerating development and deployment.
  • Geo-distribution: Services can be deployed to data centers around the world.
  • Disaster Recovery: Cloud platforms provide tools and replication capabilities to support business continuity.

CapEx vs. OpEx

Traditional IT relies on Capital Expenditure (CapEx)—large upfront investments in physical infrastructure. Cloud computing shifts spending to Operational Expenditure (OpEx)—ongoing costs based on actual usage. This model offers greater financial flexibility and predictability.

Consumption-Based Model

Cloud providers use a consumption-based pricing model, meaning customers are billed for resources actually used rather than reserved capacity. This reduces waste and aligns costs with business needs.

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