第 4 章，共 5 章12% 占考试比重
Virtualization and Cloud Computing
Virtualization and cloud services let organizations run workloads flexibly and efficiently. This chapter explains hypervisors, containers, the main cloud service and deployment models, and the resource planning behind them.
Virtualization Basics
Virtualization abstracts physical hardware so multiple operating systems can run on one machine. The hypervisor is the software layer that makes this possible.
The hypervisor manages VMs
It abstracts hardware and allocates CPU, memory, and storage to virtual machines.
Type 1 runs on bare metal
A bare-metal hypervisor installs directly on hardware for enterprise performance.
Type 2 runs on a host OS
A hosted hypervisor runs as an application on top of an existing operating system.
Isolation aids testing
VMs isolate environments so labs and development do not affect the host.
Containers vs. Virtual Machines
Containers offer a lighter alternative to full VMs by sharing the host kernel while still isolating applications.
Containers share the host kernel
They package an app and dependencies to run consistently across environments.
VMs include a full guest OS
Each VM carries its own operating system, making it heavier than a container.
Containers start fast and scale well
Their light footprint suits microservices and rapid deployment.
Choose based on isolation needs
Full VMs give stronger isolation; containers give density and speed.
Cloud Service Models
Cloud providers deliver computing at different levels of abstraction, from raw infrastructure to finished applications.
IaaS delivers infrastructure
Customers get virtual compute, storage, and networking they manage themselves.
PaaS delivers a platform
Developers deploy applications without managing the underlying OS and servers.
SaaS delivers applications
Users access fully managed software like webmail through a browser.
Responsibility shifts by model
Higher-level services move more management burden to the provider.
Cloud Deployment and Characteristics
Beyond service models, clouds differ in who owns them and share common defining traits that guide planning.
Public clouds are multi-tenant
A provider hosts shared infrastructure used by many customers.
Private clouds are dedicated
Infrastructure serves a single organization for control and compliance.
Hybrid combines both
Hybrid cloud links on-premises and public resources so workloads can move.
Elasticity and measured service
Resources scale with demand and usage is metered for pay-as-you-go billing.
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Last updated: July 2026