A2.1.1 · Network fundamentals

A2.1.1 · 网络基础

Types of Network

网络的类型

The WiFi connecting every device in your house, the link joining a company's offices across three countries, the Bluetooth pairing your phone to your headphones, and a secure tunnel letting someone work from home, are all networks, but they solve four genuinely different problems.

连接家里每一台设备的 WiFi、把公司三个国家的办公室连接起来的链路、把手机和耳机配对的蓝牙,以及让人在家也能安全办公的加密隧道,全都是网络,但它们解决的是四个截然不同的问题。

Core for SL & HL SL 与 HL 核心内容 Typically 2–4 marks · AO1 通常 2–4 分 · AO1 Command term: describe 命令词:describe(描述)

Explainer

讲解

A network links two or more devices together so they can exchange data and share things like files, printers and an internet connection, rather than each device working in total isolation.

网络把两台或以上的设备连接在一起,使它们能够交换数据,并共享文件、打印机、互联网连接等资源,而不是让每台设备完全孤立地运作。

Networks are classified mainly by how far apart the devices they connect actually are, and the range involved changes almost everything else about them: how fast they run, what technology carries the signal, and what they're actually used for.

网络主要依据其所连接设备之间的实际距离来分类,而这个范围几乎决定了其他一切特性:运行速度、承载信号所用的技术,以及它们实际的用途。

Explainer

讲解

Comparing the four types

比较四种网络类型

Each type has its own typical range, purpose and connecting technology. None of the four is simply "the best network," each one is built for a different scale of problem.

每种类型都有各自典型的范围、用途和连接技术。这四种类型中没有哪一种是单纯"最好的网络",每一种都是为了解决不同规模的问题而设计的。

PAN: Personal area network; 个人局域网
LAN: Local area network; 局域网
WAN: Wide area network; 广域网
VPN: Virtual private network; 虚拟专用网络

Type	Typical range	Purpose	Common technology
PAN	Up to about 10 metres	Connecting an individual's own personal devices to each other	Bluetooth, USB, Wi-Fi Direct
LAN	A single building or site	Sharing files, printers and internet access among devices in one location	Ethernet cabling, WiFi
WAN	Cities, countries or continents	Connecting separate LANs together over long distances	Fibre-optic backbones, leased lines, or a VPN running over the internet
VPN	Unlimited, runs over the existing internet	Creating a secure, private connection across a network the organisation doesn't own or control	Encryption over a public internet connection

类型	典型范围	用途	常见技术
PAN	约 10 米以内	连接个人自己的各种设备	蓝牙、USB、Wi-Fi Direct
LAN	单个建筑物或场地	在同一地点的设备之间共享文件、打印机和互联网连接	以太网布线、WiFi
WAN	跨城市、国家或洲际	将分散在各地的局域网通过长距离连接起来	光纤骨干网、专线,或通过互联网运行的 VPN
VPN	不受限制,基于现有互联网运行	在组织不拥有或不控制的网络上建立一条安全、私密的连接	在公共互联网连接上加密

Range alone explains most of the practical differences: a PAN is deliberately too short-range to reach beyond arm's length, while a WAN and a VPN are both built specifically to work when the distance involved rules out a single physical network entirely.

范围本身就能解释大部分的实际差异:PAN 被刻意设计成短距离,超出手臂范围就无法覆盖,而 WAN 和 VPN 则专门为距离过远、单一物理网络已无法覆盖的情况而设计。

Worked example

示例讲解

All four in one day

一天之内用上全部四种

Zoe works for a company with offices in three different countries, and uses all four network types before lunch without ever thinking about it. Click each one to see exactly where it shows up in her morning.

Zoe 在一家于三个不同国家设有办公室的公司工作,午饭前她其实已经在不知不觉中用上了全部四种网络类型。点击每一种,看看它在她的早晨中具体出现在哪里。

Check your understanding

检验你的理解

A design studio with 20 staff in one building wants every computer to reach the same shared printer and file server, but never needs to talk to any other building or site. Which network type actually fits this need?

某设计工作室有 20 名员工在同一栋建筑物内工作,希望每台电脑都能访问同一台共享打印机和文件服务器,但从不需要与其他建筑物或场地通信。哪种网络类型真正适合这个需求?

Common mistake

常见错误

A recurring confusion this statement's own wording is written to guard against 这一考纲陈述本身的措辞正是为了防范这个反复出现的混淆

RecurringA common weak answer treats "WAN" and "the internet" as the same thing. A WAN is a network that interconnects an organisation's own separate LANs over a long distance, whether that's over its own dedicated infrastructure or, as is now more common, over a VPN running across the public internet. The internet itself is a single, specific, enormous network of networks that nobody owns, a WAN is any organisation's own private long-distance network, which today usually happens to use the internet as its carrier, but conceptually the two are not the same thing.

反复出现一个常见的薄弱答案会把"WAN"和"互联网"当成同一件事。WAN 是一种把某个组织自己分散的局域网通过长距离连接起来的网络,无论是通过其自有专用基础设施,还是像现在更常见的那样,通过运行在公共互联网上的 VPN。互联网本身是一个特定的、庞大的、没有人拥有的网络的网络,而 WAN 是任何组织自己的私有长距离网络,如今通常恰好以互联网作为其载体,但从概念上讲,两者并不是同一回事。

Treats them as identical: "A WAN is just another name for the internet." Misses that a WAN is a specific organisation's own private network spanning a large distance, while the internet is a single global network that isn't owned or controlled by any one organisation.

把两者当作同一回事: "WAN 只是互联网的另一个说法。" 忽略了 WAN 是某个特定组织自己跨越长距离的私有网络,而互联网是一个不为任何单一组织所拥有或控制的全球统一网络。

✓

Names the actual relationship: "A WAN connects an organisation's own LANs across a long distance, and many modern WANs use the public internet (via a VPN) to do this, but a WAN is still the organisation's own private network, not the internet itself." Correctly separates the two ideas while explaining why they're easy to conflate.

准确说明两者的真实关系: "WAN 把一个组织自己的局域网通过长距离连接起来,许多现代 WAN 会借助公共互联网(通过 VPN)来实现这一点,但 WAN 依然是该组织自己的私有网络,而不是互联网本身。" 正确地区分了这两个概念,同时说明了它们为何容易被混淆。

Revision questions

复习题

Past-paper style. Write an answer, then reveal the marking points and mark yourself.

采用历年真题风格。写下答案,然后展开评分要点给自己打分。

Question 1 · 2 marks 第 1 题 · 2 分

[2]Name two network types that only cover a small physical range.

[2]说出两种只覆盖较小物理范围的网络类型。

Question 2 · 2 marks 第 2 题 · 2 分

[2]Outline what a VPN is mainly used to achieve.

[2]概述 VPN 主要用来实现什么目的。

Question 3 · 4 marks 第 3 题 · 4 分

[4]A multinational company wants its five office branches, spread across three continents, to securely share files and applications. Describe a suitable network solution and justify your answer.

[4]某跨国公司希望其分布在三大洲的五个分支办公室能够安全地共享文件与应用程序。描述一个合适的网络解决方案,并为你的答案提供理由。

Flashcards

记忆卡片

Active recall for this statement’s key terms.

针对本条考纲陈述关键术语的主动回忆练习。

Keep this statement’s practice with you

把这条考纲陈述的练习保存下来

Free account: unlock every revision question and flashcard for A2.1.1, and every other IB CS 2027 statement.

免费账户:解锁 A2.1.1 以及所有其他 IB CS 2027 考纲陈述的全部复习题和记忆卡片。