Cloud Concepts

What is cloud computing?

Using on-demand computing services such as servers, storage, and networking over a network instead of buying and maintaining all the hardware yourself. Azure is a public cloud provider.

What is the shared responsibility model?

Security and management duties are divided between Microsoft and the customer. Microsoft always protects the physical infrastructure; you remain responsible for data, identities, and how you configure access.

Which responsibilities always remain with the cloud customer?

Protecting and classifying data, managing user accounts and permissions, and deciding how resources are configured. The provider does not take over your accountability for the data.

What is a public cloud?

Cloud infrastructure owned by a provider and offered to multiple customers. Each customer rents services on shared provider infrastructure with logical isolation.

What is a private cloud?

Cloud infrastructure dedicated to one organisation, hosted on-premises or by a third party. Dedicated does not necessarily mean physically located in your office.

What is a hybrid cloud?

An environment combining private or on-premises infrastructure with public cloud services. Example: company servers connected to Azure resources.

Public cloud vs hybrid cloud: what's the decisive difference?

Hybrid combines private/on-premises resources with public cloud; public cloud alone does not establish that combination. Connecting an office network to Azure does not automatically mean every workload runs in Azure.

What is a multicloud approach?

Using services from more than one public cloud provider, such as Azure and AWS. It differs from hybrid, which combines public and private/on-premises environments.

What is capital expenditure (CapEx)?

Upfront purchases treated as capital investment, such as buying your own servers or datacentre equipment. Contrast with ongoing cloud consumption as OpEx.

What is operating expenditure (OpEx)?

Recurring operational costs, such as monthly cloud charges based on usage. Cloud costs can also contain commitments and fixed fees; not all charges fluctuate perfectly with use.

What does consumption-based pricing mean?

Charges depend on metered use of services, such as compute hours, storage quantity, and data transfer. It reduces the need to buy maximum server capacity upfront.

What is pay-as-you-go in Azure?

A pricing arrangement that bills eligible services according to their metered consumption without a long-term reservation commitment. Resources that stay provisioned may still generate charges while idle.

What are Azure reservations?

A commitment to qualifying capacity or usage for a term in exchange for potential price savings compared with pay-as-you-go. They improve cost predictability, but require commitment.

What are Azure Spot Virtual Machines?

Spare Azure compute capacity offered at discounts but subject to eviction when Azure needs capacity or prices exceed the limit. Appropriate for interruptible workloads, not critical always-on apps.

What is high availability (HA)?

Designing services to remain operational with minimal interruption when a component fails. Example: redundant app instances across availability zones.

What is scalability?

The ability to increase or decrease computing capacity to handle different workloads. Can be vertical (bigger machine) or horizontal (more machines).

What is vertical scaling (scale up/down)?

Changing the resources of one instance, such as upgrading a VM from 2 to 8 vCPUs. The number of VM instances need not change.

What is horizontal scaling (scale out/in)?

Increasing or decreasing the number of instances, such as growing from two VMs to six. Capacity changes by adding/removing machines rather than resizing one.

What is elasticity?

Quickly, often automatically, adjusting provisioned capacity to match demand and shrinking it when demand drops. Scaling is ability; elasticity is responsive adjustment.

What is cloud reliability?

The ability of a system to recover from failures and continue functioning. Redundancy, monitoring, backups, and disaster recovery support reliability.

What is performance predictability in cloud computing?

Being able to forecast application performance based on performance measurements, architecture, and resource selection. Reliability instead concerns working despite failures.

What is cost predictability in cloud computing?

Estimating and forecasting expenditure with pricing, usage trends, and budgets. It does NOT mean the monthly bill is guaranteed to remain the same.

What is fault tolerance?

The ability to continue operating when part of a system fails, often by using redundant components. It supports high availability.

What is disaster recovery (DR)?

Plans and mechanisms for restoring applications/data after a serious failure such as a regional outage. DR often involves another region and recovery objectives.

High availability vs disaster recovery?

HA reduces downtime during common failures; DR restores service after major disasters. Having multiple instances in one region does not automatically guarantee regional disaster recovery.

What is cloud manageability?

The ability to control resources using a portal, APIs, CLI, PowerShell, templates, automation, and monitoring without manually accessing the physical hardware.

What are cloud security and governance benefits?

Cloud services offer centralised policies, identity controls, security monitoring, and compliance capabilities. Customers must configure and manage those controls correctly.

What is serverless computing?

You deploy code or a workload without maintaining its underlying servers; the provider handles infrastructure and much of scaling. Servers still exist behind the scenes.

What is Infrastructure as a Service (IaaS)?

Rent infrastructure such as VMs, networks, and disks. Microsoft manages physical hosts; YOU maintain the guest OS, installed applications, and their configuration.

What is Platform as a Service (PaaS)?

Deploy applications or databases onto a managed platform. Microsoft manages underlying OS/runtime infrastructure; YOU manage application code, configuration, and data.

What is Software as a Service (SaaS)?

A ready-to-use application delivered by a provider, such as Microsoft 365. The provider operates the software; YOU manage users, access, and your data.

IaaS vs PaaS: who patches the guest OS?

IaaS: you patch and manage the VM operating system. PaaS: provider patches the platform's operating system; you still secure code, access, and data.

When is IaaS preferable to PaaS?

When you need guest OS control, custom drivers, or software requiring deep system-level configuration. Choose PaaS when the main goal is to deploy an app without server administration.

What is the best cloud model for ready-to-use email software?

SaaS. The provider hosts, maintains, and updates the application; your organisation manages accounts, settings, and information.

What service model describes Azure SQL Database?

PaaS: Microsoft maintains the database platform and OS; the customer manages database content, access permissions, and application-specific configuration.

What service model describes an Azure Virtual Machine?

IaaS: the customer controls and patches the guest operating system and software, while Microsoft maintains physical infrastructure.

What service model describes Azure App Service?

PaaS: deploy and manage your web application without managing the underlying host OS or hardware.

Does using a cloud provider eliminate ALL security responsibilities?

No. Shared responsibility always leaves the customer accountable for its data, identities, user access, and configuration decisions.