Introduction to Computer Networks

What Is a Network?

A network is two or more connected computers (hosts) that share data, applications, printers, and internet connections. Underneath every shared file and printed page, computers are exchanging nothing more than 1s and 0s — binary is the actual language of the wire.

Data

Exam angleWhenever a question describes devices exchanging resources — files, printers, internet access — over a connection, it's describing a network by definition, regardless of size.

Local Area Network (LAN)

A LAN covers a small geographic area — an office, a building, a home — and allows resource sharing within that limited footprint. Large LANs are often divided into workgroups, logical segments that keep traffic organized by department or team.

Key pointA router connects LANs together, allowing communication between departments — for example, letting Sales talk to Marketing across what would otherwise be two separate networks.

Common Network Components

Every network is built from the same three roles. Click a card to flip it.

Common server types

Network Types by Scale

From a Bluetooth earbud to the entire internet — scale changes the technology. Flip each card for the exam-relevant detail.

WAN Technologies

How enterprises actually move traffic between sites, expand each for what the exam expects you to know.

Network Architectures

Every network is organized one of two ways: everyone is equal, or someone is in charge.

Peer-to-Peer

No central authority
Each host can act as both client and server
Poor scalability
Weak security

Client-Server

Centralized server manages security, authentication, resource access
Highly scalable
Better security
Easier management

Physical Network Topologies

The physical shape of the cabling changes everything about cost, fault tolerance, and troubleshooting. Explore each one below.

Mesh connection formula — n(n−1)/2, try it: n =

Backbone & Segments

The backbone is the high-speed central connection — often Gigabit or faster — that ties every segment and server together. A segment is simply a smaller portion of the network that branches off that backbone. This page's own layout mirrors it: the sidebar is the backbone, each section is a segment.

Service Entry Points

The Demarcation Point (Demarc) is the line where the provider's responsibility ends and yours begins — typically terminated at a smart jack inside the building.

Exam angleIf a question asks "whose problem is it," the demarc is the boundary that answers it. Anything before it: the carrier's issue. Anything after it: yours.

Virtual Networking

Modern networks don't only run on physical hardware — much of it now runs as software.

Three-Tier Model

The classic enterprise design splits switching duties into three layers. Click a layer to expand it.

Collapsed coreIn small or medium networks, Core and Distribution are combined into one layer to save cost and complexity.

Spine and Leaf Architecture

Used in modern data centers. Every leaf switch connects to every spine switch, which means any server can reach any other server in exactly two hops — always. Leaf switches connect servers; spine switches connect leaves. It's extremely fast, extremely scalable, and built for virtualization.

Traffic Flow

Toggle between the two traffic patterns every network diagram needs to show.

Exam Check

Six quick questions pulled straight from this chapter. No pressure — just a gut check.

Score: 0 / 0

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