MSDEVBUILD / azure

Hybrid and Multi-cloud

Public cloud shared by many, pay as you go Private cloud just for one organisation Hybrid cloud both, securely connected
Hybrid cloud connects your own building to the public cloud, so data can travel safely between them.

😟 THE PROBLEM

Patient records must stay in the hospital, but the new AI tools are in the cloud.

😊 THE SOLUTION

Go hybrid: keep the records on-premises and connect them securely to Azure.

  • Some data must stay on-premises✓ Keep it there and use cloud for the rest
  • Two worlds that cannot talk✓ Connect them with VPN Gateway or ExpressRoute
  • Two sets of tools to manage✓ Azure Arc manages both from one place
🛠️ Solved with: Hybrid cloud + Azure Arc
Module 1: Cloud Concepts ⏱ 9 min read Updated 11 Nov 2026

Quick answer

A hybrid cloud combines a public cloud with a private cloud or on-premises infrastructure and lets data and applications move between them, so each workload runs where it fits best. Multi-cloud means using two or more public cloud providers, for example Azure and AWS. Azure Arc lets you manage resources across all of these from Azure.

Exam objective: 1.1.3 Define cloud models, including public, private, and hybrid. 1.1.4 Identify appropriate use cases for each cloud model. (Skills measured as of July 20, 2026)

Start with a question

What if a hospital must keep patient records in its own building, but wants to use cloud AI to analyse scans?

It does not have to pick one world. It can keep the records system at home and still use the cloud for the parts that benefit from it, connected safely.

That “best of both worlds” approach is hybrid cloud, and it is how most large organisations actually run today.

Explain it like I’m 10

The technical explanation

Hybrid cloud is a computing environment that combines a public cloud with a private cloud or on-premises infrastructure, allowing data and applications to be shared between them. The organisation decides, workload by workload, where each piece runs.

Multi-cloud means using two or more public cloud providers, for example Azure for applications and another provider for a specific analytics tool. It often happens through acquisitions or team preferences.

  1. 1 On-premises datacenter

    Core systems and regulated data stay here.

  2. 2 Secure connection

    VPN Gateway (encrypted over the internet) or ExpressRoute (private circuit).

  3. 3 Azure

    Web apps, analytics, AI, backup and disaster recovery.

  4. 4 One control plane

    Azure Arc + Azure Policy + Azure Monitor across both.

A typical hybrid architecture

Choosing a cloud model: use cases

The exam objective asks you to identify use cases for each model. Here they are side by side:

Public cloud

  • New web and mobile apps
  • Unpredictable or seasonal traffic
  • Dev/test environments
  • Start-ups with no hardware budget

Private cloud

  • Strict regulatory control of hardware
  • Highly customised infrastructure
  • Large, steady workloads on owned hardware

Hybrid cloud

  • Some data must stay on-premises
  • Gradual migration to the cloud
  • Cloud bursting for peaks
  • Cloud backup and disaster recovery
Matching workloads to cloud models

Azure Arc: managing everything from one place

Azure Arc projects resources running outside Azure (on-premises Windows and Linux servers, Kubernetes clusters, SQL Server instances, even VMs in other clouds) into Azure Resource Manager. Once connected, you can tag them, apply Azure Policy, protect them with Microsoft Defender for Cloud, monitor them with Azure Monitor and control access with Azure RBAC, exactly like native Azure resources.

Architect level Hybrid design patterns architects actually use
  • Tiered hybrid: front ends in the cloud, back-end systems of record on-premises. Watch the chatty calls across the link, because latency adds up.
  • Partitioned multi-cloud: different workloads on different clouds, each fully self-contained. This is simpler than spreading one app across clouds.
  • Cloud bursting: needs the app to be stateless or to have data close at hand, plus pre-tested capacity in the cloud. Often harder in practice than on slides.
  • Backup and DR to cloud: Azure Backup and Azure Site Recovery replicate on-premises workloads to Azure. This is often the first and lowest-risk hybrid step.
  • Edge: run workloads on-premises with Azure Local or Arc-enabled Kubernetes for latency or disconnected scenarios, managed centrally.

Key cross-cutting decisions are identity (Entra ID with hybrid sync), DNS resolution across environments, IP address planning with no overlaps, and egress cost on data that crosses boundaries.

Real-world business scenario

Enterprise / Insurance

A national insurance company

The problem
Policy administration runs on a mainframe that cannot move, but the company wants a modern customer portal, AI-driven claims triage and cloud backup.
What they used
Customer portal and AI services in Azure, connected to the mainframe via ExpressRoute. Azure Backup for on-premises servers. All servers onboarded to Azure Arc for unified policy and monitoring.
Why that choice
The mainframe stays put; everything customer-facing gets cloud agility; one governance model covers both environments.
The result
Claims are triaged in minutes, the portal scales during storm seasons, and auditors review a single set of policies.

When to use it and when not to

✓ Use it when…

  • Part of your estate must stay on-premises (regulation, latency, legacy) but other parts benefit from cloud.
  • You are migrating gradually and need both worlds to work together for months or years.
  • You want cloud-based backup, disaster recovery or burst capacity for on-premises systems.
  • Multi-cloud: a specific provider has a service you truly need, or an acquisition brought another cloud.

✕ Think twice when…

  • You have no on-premises requirement. A single public cloud is simpler.
  • Multi-cloud "just in case". It multiplies skills, tooling and security effort.
  • Splitting one tightly coupled application across environments with high latency between them.

↔ Alternatives to consider

  • **Go all-in on public cloud** if nothing needs to stay on-premises.
  • **Private cloud only** for fully regulated, stable estates.
Ready for more?The full lesson adds the technical explanation, when to use it, interview questions and revision notes.

Interview preparation

Say your answer out loud first, then open the model answer. Interviewers care more about your reasoning than the exact words.

Beginner What is a hybrid cloud?

Model answer

It is a mix of public cloud and private or on-premises infrastructure that work together. For example, a company keeps its customer database in its own datacenter but runs its website in Azure, and the two are securely connected.

Interviewer follows up

How are they connected?

You

Usually with a site-to-site VPN over the internet (Azure VPN Gateway) or a private dedicated connection (Azure ExpressRoute). Identity is often unified too, with Microsoft Entra ID synchronised from on-premises Active Directory.

Intermediate What is the difference between hybrid cloud and multi-cloud?

Model answer

Hybrid is about combining on-premises or private infrastructure with public cloud. Multi-cloud is about using more than one public cloud provider. An organisation can be both, with on-premises servers plus Azure and AWS.

Experienced developer What is the biggest operational challenge of hybrid and multi-cloud, and how do you address it?

Model answer

Fragmentation. Different consoles, policies, identity systems, monitoring and skill sets for each environment, which leads to inconsistent security. I would standardise identity on one provider, use a single control plane where possible (Azure Arc to project on-premises and other-cloud servers and Kubernetes into Azure, then apply Azure Policy, Defender for Cloud and Azure Monitor consistently), and use infrastructure as code with tools such as Terraform for multi-cloud deployments. Also be deliberate. Multi-cloud for its own sake doubles complexity.

Interviewer follows up

Is multi-cloud a good way to avoid vendor lock-in?

You

Sometimes, but it has a price. To be truly portable you limit yourself to the lowest common denominator and give up many managed services. A pragmatic approach is to pick a primary cloud, use its managed services, and design for portability only where the business risk justifies it.

Scenario A retailer's on-premises order system copes fine except during Black Friday. What hybrid pattern could help?

Model answer

Cloud bursting. The order system keeps running on-premises normally, and during the peak extra application instances run in Azure, connected back to on-premises over VPN or ExpressRoute. They pay for the cloud capacity only during the peak.

Test yourself with exercises

4 original practice questions in the AZ-900 style. Pick your answers, then check them. You will see why each option is right or wrong. Score 75% or more and this topic is marked complete.

Question 1

Question 1 of 4

A company must keep its customer database on-premises for compliance, but wants to host its public website in Azure and let the website read from that database.

Which cloud model is this?

Question 2

Question 2 of 4

An organisation uses both Microsoft Azure and another public cloud provider. What is this approach called?

Question 3

Question 3 of 4

Which Azure service lets you manage on-premises servers and servers in other clouds with Azure tools such as Azure Policy?

Question 4

Question 4 of 4 · Select 2

Which TWO are benefits of a hybrid cloud?

Quick revision

Key points

  • Hybrid = public cloud + private cloud/on-premises, connected and working together.
  • Multi-cloud = more than one public cloud provider.
  • Hybrid gives flexibility. Keep what must stay; move what benefits from cloud.
  • Connectivity options are VPN Gateway (over the internet, encrypted) and ExpressRoute (private, dedicated).
  • Azure Arc manages servers, Kubernetes and data services anywhere from Azure.

Important terminology

Hybrid cloud
A combination of public cloud with private cloud or on-premises infrastructure, connected so workloads and data can interact.
Multi-cloud
Using services from two or more public cloud providers.
Cloud bursting
Running normally on-premises and "bursting" extra demand into the public cloud during peaks.
Azure Arc
Extends Azure management, governance and security to servers, Kubernetes and data services running anywhere.
ExpressRoute
A private, dedicated connection between your network and Azure that does not travel over the public internet.

Common mistakes

  • Treating hybrid and multi-cloud as the same thing.
  • Forgetting that hybrid adds complexity and needs unified identity, security and monitoring.

Exam tips

  • "Keep some data on-premises for compliance while using the cloud for the rest" = hybrid cloud.
  • "Manage on-premises and other-cloud servers from Azure" = Azure Arc.
  • Use cases. Public for new and variable workloads, private for strict control, hybrid when you need both.

Five quick revision questions

  1. 1.What two environments does a hybrid cloud combine?Show

    Public cloud and private cloud/on-premises infrastructure.

  2. 2.What does multi-cloud mean?Show

    Using services from more than one public cloud provider.

  3. 3.What is cloud bursting?Show

    Running on-premises normally and sending extra peak demand to the public cloud.

  4. 4.Which Azure service manages servers running outside Azure as if they were Azure resources?Show

    Azure Arc.

  5. 5.Which Azure service provides a private, dedicated connection that does not use the public internet?Show

    Azure ExpressRoute.

Official references

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