Core 1 Domain 4: Virtualization and Cloud Computing (11%)¶

Overview¶

This is the smallest Core 1 domain, but it matters more than its weight suggests. Help desk technicians now spin up test VMs, support virtual desktops, and field questions about cloud apps every day. The exam stays at the concept level: why you would use a VM, what kind of hypervisor fits, what a container is, and how cloud services are delivered and billed.

The objectives are:

• 4.1 Explain virtualization concepts.
• 4.2 Summarize cloud computing concepts.

4.1 Virtualization Concepts¶

What virtualization is¶

Virtualization lets one physical computer (the host) run several isolated operating systems (guests, or virtual machines). A layer of software called the hypervisor shares the host's CPU, memory, storage, and network among the guests. Each guest believes it has its own hardware.

Why we use virtual machines¶

Hypervisor types¶

flowchart TB
    subgraph T1["Type 1 - bare metal"]
        direction TB
        V1["VM"] --- V2["VM"]
        H1["Hypervisor"]
        HW1["Hardware"]
    end
    subgraph T2["Type 2 - hosted"]
        direction TB
        V3["VM"] --- V4["VM"]
        H2["Hypervisor application"]
        OS2["Host operating system"]
        HW2["Hardware"]
    end
    V1 --> H1 --> HW1
    V3 --> H2 --> OS2 --> HW2

A Type 1 hypervisor sits directly on the hardware. A Type 2 hypervisor runs as an application inside a host OS, adding an extra layer.

Hyper-V is a common trick question. When you enable it on Windows 11 Pro it looks like an app, but it actually installs as a Type 1 hypervisor underneath Windows.

Containers¶

Containers package an application with its libraries and settings, but share the host's OS kernel instead of carrying a full OS.

Containers are why "it works on my machine" became "it works everywhere." A Linux container needs a Linux kernel, so on Windows it runs inside a lightweight VM (WSL 2 or Hyper-V).

Desktop virtualization and VDI¶

VDI (virtual desktop infrastructure) hosts user desktops as VMs in the data center or cloud. Users connect from a thin client, laptop, or browser.

• Benefits - Central management and patching, data stays in the data center, works on cheap or personal devices, fast recovery if a laptop is lost.
• Costs - Depends on the network. Poor latency means a poor user experience. Server and licensing costs move to the back end.
• Examples - Azure Virtual Desktop, Amazon WorkSpaces, Citrix, VMware Horizon.

Requirements for virtualization¶

4.2 Cloud Computing Concepts¶

📖 NIST SP 800-145 - The NIST Definition of Cloud Computing - The standard definition behind the service and deployment models

Deployment models¶

Service models¶

The service model decides who manages what. The higher you go, the less you manage.

flowchart LR
    subgraph IaaS
        I1["You: apps, data, runtime, OS"]
        I2["Provider: virtualization, servers, storage, network"]
    end
    subgraph PaaS
        P1["You: apps, data"]
        P2["Provider: runtime, OS, virtualization, hardware"]
    end
    subgraph SaaS
        S1["You: data, users, settings"]
        S2["Provider: the whole application stack"]
    end
    IaaS --> PaaS --> SaaS

The split of responsibility shifts toward the provider as you move from IaaS to PaaS to SaaS.

Memory hook: IaaS gives you a virtual server. PaaS gives you a place to run code. SaaS gives you a finished app you log in to.

Cloud characteristics¶

Elasticity vs scalability: scalability is the ability to grow. Elasticity is growing and shrinking automatically as load changes. The exam's word is "elasticity."

Support angle¶

Cloud questions on A+ are usually framed from the help desk:

• A user cannot open a SaaS app - check internet access, identity (MFA, account lockout), license assignment, and the provider status page before blaming the PC.
• Sync conflicts - two devices edited the same file offline. The sync client keeps both copies with different names.
• Unexpected cloud bill - egress charges or resources left running. Metered billing means idle VMs still cost money.

Exam Tips and Traps¶

1. Type 1 = bare metal (ESXi, Hyper-V). Type 2 = runs on an OS (VirtualBox, Workstation).
2. Enable VT-x or AMD-V in UEFI when a hypervisor says virtualization is not available.
3. Containers share the host kernel. VMs each have their own OS.
4. Sandbox is the answer for testing suspicious files safely.
5. VDI keeps data in the data center. A lost laptop exposes nothing.
6. SaaS = you only manage data and users. IaaS = you patch the OS.
7. Community cloud is shared by organizations with a common mission or compliance need.
8. Egress is the charge for data leaving the cloud.
9. Elasticity is automatic scale up and down.
10. Multitenancy means shared infrastructure with logical isolation.

Related Notes¶

• 03 - Hardware - UEFI virtualization settings and CPU architecture
• 06 - Operating Systems - Configuring cloud productivity tools in Core 2
• Fact Sheet - Quick reference tables