Networks & Technologies

Networking Fundamentals, Network Types, Topologies, Hardware, and Connectivity

What Is a Computer Network?

A computer network is a collection of two or more devices connected together so they can communicate and share resources.

Networks allow computers and other devices to exchange data efficiently, whether they are in the same room or located around the world.

A network can include:

Modern businesses rely heavily on networks for communication, collaboration, and resource sharing.

Why Networks Are Important

Networks provide numerous benefits, including:

Without networking, each computer would operate independently, making collaboration much more difficult.

Components of a Network

Every network consists of several basic components.

Common components include:

Each component performs a specific role in enabling communication.

Network Interface Card (NIC)

A Network Interface Card (NIC) is the hardware component that allows a device to connect to a network.

Every network-enabled device contains at least one NIC.

Functions of a NIC include:

NICs may support:

MAC Address

A Media Access Control (MAC) address is the unique physical address assigned to every network interface.

Characteristics include:

Unlike IP addresses, MAC addresses normally do not change.

Network Types

Networks are categorized according to their size and geographical coverage.

Common network types include:

Personal Area Network (PAN)

A Personal Area Network (PAN) connects devices belonging to a single individual over a short distance.

Examples include:

PANs typically cover only a few meters.

Local Area Network (LAN)

A Local Area Network (LAN) connects devices within a limited geographic area, such as:

Characteristics:

LANs are the most common type of business network.

Wireless Local Area Network (WLAN)

A Wireless Local Area Network (WLAN) is simply a LAN that uses wireless communication instead of Ethernet cables.

Advantages include:

Wireless networks rely primarily on Wi-Fi technology.

Metropolitan Area Network (MAN)

A Metropolitan Area Network (MAN) connects multiple LANs across a city or metropolitan region.

Examples include:

A MAN is larger than a LAN but smaller than a WAN.

Wide Area Network (WAN)

A Wide Area Network (WAN) connects multiple LANs over large geographic distances.

Characteristics include:

The Internet is the world’s largest WAN.

Comparing Network Types
NetworkCoverage AreaExample
PANPersonal workspaceBluetooth devices
LANBuildingOffice network
WLANBuilding (wireless)Home Wi-Fi
MANCityUniversity campus
WANCountry or worldwideInternet
Network Topologies

A network topology describes how devices are physically or logically connected.

Understanding topologies helps administrators design efficient and reliable networks.

Common topologies include:

Bus Topology

In a bus topology, every device connects to one central communication cable.

Advantages:

Disadvantages:

Bus topologies are rarely used in modern networks.

Star Topology

A star topology connects every device to a central switch or hub.

Advantages:

Disadvantages:

Star is the most common network topology today.

Ring Topology

A ring topology connects devices in a circular path.

Data travels around the ring until it reaches its destination.

Advantages:

Disadvantages:

Mesh Topology

A mesh topology provides multiple communication paths between devices.

Advantages:

Disadvantages:

Mesh networks are common in critical environments where uptime is essential.

Hybrid Topology

A hybrid topology combines two or more network topologies.

Most enterprise networks use hybrid designs because they provide flexibility and scalability.

Wired Networking

Wired networks use physical cables to transmit data.

Advantages include:

Ethernet is the most widely used wired networking technology.

Wireless Networking

Wireless networks transmit data using radio waves instead of cables.

Advantages include:

Disadvantages include:

Network Transmission Media

Transmission media carries data between network devices.

Two major categories exist:

Twisted Pair Cable

Twisted pair cable is the most common networking cable.

Examples include:

Advantages:

Most office LANs use twisted-pair Ethernet cables.

Fiber-Optic Cable

Fiber-optic cable transmits data using pulses of light.

Advantages include:

Fiber is commonly used for:

Wireless Signals

Wireless communication uses radio frequencies.

Common wireless technologies include:

Wireless signals eliminate physical cabling but require proper security and signal management.

Best Practices

Key Terms

Exam Tips

Network Devices, TCP/IP, Network Protocols, IP Addressing, and Network Services

Network Devices

Modern networks use several specialized devices to allow computers and other equipment to communicate efficiently.

Each device performs a unique function within the network.

Common networking devices include:

Hub

A hub is one of the simplest networking devices.

It receives incoming data and broadcasts it to every connected device regardless of the intended destination.

Characteristics include:

Because hubs create unnecessary traffic, they have largely been replaced by switches.

Switch

A switch intelligently forwards data only to the device for which it is intended.

Unlike a hub, a switch learns the MAC addresses of connected devices and builds a MAC address table.

Advantages include:

Most modern Ethernet LANs use switches.

Router

A router connects different networks together.

The most common example is a home router connecting a local network to the Internet.

Functions of a router include:

Routers are essential for Internet connectivity.

Wireless Access Point (WAP)

A Wireless Access Point (WAP) allows wireless devices to connect to a wired network.

Wireless access points:

Businesses often install multiple access points to provide complete wireless coverage.

Wireless Router

A wireless router combines several networking functions into one device.

Most wireless routers include:

Wireless routers are common in homes and small offices because they provide both wired and wireless connectivity.

Modem

A modem connects a local network to an Internet Service Provider (ISP).

The modem converts signals between the ISP’s network and the customer’s local network.

Depending on the service, a modem may support:

Without a modem or equivalent connection device, most homes and businesses cannot access the Internet.

Firewall

A firewall is a security device that monitors and filters incoming and outgoing network traffic.

Firewalls help prevent unauthorized access while allowing legitimate communication.

Firewalls can be:

Many modern routers include built-in firewall functionality.

Host-Based Firewall

A host-based firewall protects a single computer.

Examples include:

Each computer manages its own firewall settings.

Network-Based Firewall

A network-based firewall protects an entire network.

Characteristics include:

Businesses commonly deploy network firewalls at the edge of their networks.

Access Control Lists (ACLs)

Firewalls use Access Control Lists (ACLs) to determine whether network traffic should be allowed or blocked.

ACL rules may specify:

Most firewalls use a default deny approach, blocking traffic unless it is explicitly permitted.

Networking Protocols

A network protocol is a standardized set of rules that allows devices to communicate.

Protocols ensure that computers interpret transmitted information consistently.

Without common protocols, network communication would fail.

The most widely used protocol suite today is TCP/IP, which forms the foundation of the Internet and most modern networks.

TCP/IP

Transmission Control Protocol/Internet Protocol (TCP/IP) is the standard protocol suite used for network communication.

TCP/IP allows different devices, operating systems, and networks to communicate with one another.

Although named after TCP and IP, the suite includes many different protocols that work together.

TCP/IP (DoD) Model

The TCP/IP suite is organized into four layers based on the Department of Defense (DoD) model.

The four layers are:

  1. Process/Application
  2. Host-to-Host
  3. Internet
  4. Network Access

Each layer performs specific networking functions.

Process/Application Layer

The Process/Application layer provides network services directly to user applications.

Common protocols include:

These protocols enable web browsing, email, file transfers, and other network services.

Host-to-Host Layer

The Host-to-Host layer manages end-to-end communication between devices.

The two primary protocols are:

These protocols determine how data is delivered across the network.

TCP (Transmission Control Protocol)

TCP provides reliable communication.

Features include:

Applications requiring reliable communication typically use TCP.

Examples include:

UDP (User Datagram Protocol)

UDP provides faster communication by sacrificing some reliability.

Characteristics include:

Applications commonly using UDP include:

Internet Layer

The Internet layer is responsible for logical addressing and routing.

Important protocols include:

This layer determines how packets travel between networks.

Network Access Layer

The Network Access layer defines how data is physically transmitted across the network.

Examples include:

This layer handles communication over the physical network medium.

Common Network Protocols

HTTP

Hypertext Transfer Protocol (HTTP) transfers web pages.

HTTP is not encrypted and should not be used for sensitive information.

HTTPS

Hypertext Transfer Protocol Secure (HTTPS) encrypts communication between web browsers and web servers.

HTTPS protects:

HTTPS has largely replaced HTTP for secure web browsing.

FTP

File Transfer Protocol (FTP) transfers files between computers.

FTP is commonly used to:

Traditional FTP does not encrypt transferred data.

SMTP

Simple Mail Transfer Protocol (SMTP) sends outgoing email.

Mail servers use SMTP to deliver email messages.

POP3

Post Office Protocol Version 3 (POP3) downloads email from a mail server to a local device.

Downloaded messages are often removed from the server after retrieval.

IMAP

Internet Message Access Protocol (IMAP) allows email to remain on the mail server while synchronizing messages across multiple devices.

IMAP is commonly used on smartphones, tablets, and multiple computers.

IPv4 Addressing

Every device on a TCP/IP network requires a unique IP address for communication.

An IPv4 address:

Example:

192.168.1.100

Each octet ranges from 0 to 255.

Public vs. Private IP Addresses

Public IP Address

Private IP Address

Used inside local networks.

Common private IPv4 ranges:

Private addresses cannot be routed directly over the public Internet.

IPv6

As Internet-connected devices increased, IPv4 addresses became limited.

IPv6 was developed to provide a vastly larger address space.

Characteristics:

Example:

2001:0db8:85a3::8a2e:0370:7334

MAC Address vs. IP Address
MAC AddressIP Address
Physical addressLogical address
Assigned to the NICAssigned by network configuration
Usually permanentCan change
Used within the local networkUsed for communication between networks

A MAC address identifies the hardware, while an IP address identifies the device’s location on the network.

DNS (Domain Name System)

DNS translates human-readable domain names into IP addresses.

Example:

Instead of remembering:

142.250.xxx.xxx

Users simply type:

www.google.com

DNS servers perform this translation automatically.

DHCP (Dynamic Host Configuration Protocol)

DHCP automatically assigns network configuration information to devices.

DHCP typically provides:

Automatic addressing simplifies network administration.

Default Gateway

The default gateway is the router that forwards traffic from the local network to other networks, including the Internet.

When a destination is outside the local network, the device sends traffic to the default gateway for routing.

Best Practices

Key Terms

Exam Tips

Wireless Networking, Mobile Networks, VPNs, Network Performance, and Troubleshooting

Wireless Networking

Wireless networking allows devices to communicate using radio waves instead of physical cables.

Wi-Fi is based on the IEEE 802.11 family of networking standards and is the most common wireless networking technology.

Wireless networking is widely used in:

Wireless networks provide flexibility and mobility but require proper security to protect data.

Advantages of Wireless Networking

Wireless networking offers several benefits:

These advantages make wireless networking ideal for environments where mobility is important.

Disadvantages of Wireless Networking

Wireless communication also presents challenges.

Common disadvantages include:

Proper planning helps minimize these issues.

Wi-Fi Standards

Wi-Fi standards define how wireless devices communicate.

Several IEEE 802.11 standards are commonly encountered.

IEEE 802.11b

Characteristics:

IEEE 802.11a

Characteristics:

IEEE 802.11g

Characteristics:

IEEE 802.11n (Wi-Fi 4)

Characteristics:

Wi-Fi 4 significantly improved wireless performance over earlier standards.

IEEE 802.11ac (Wi-Fi 5)

Characteristics:

IEEE 802.11ax (Wi-Fi 6)

Characteristics:

Wi-Fi 6 is designed for modern high-density wireless environments.

Frequency Bands

Wireless networks primarily use two frequency bands.

2.4 GHz

Advantages:

Disadvantages:

5 GHz

Advantages:

Disadvantages:

Modern wireless routers often support both frequency bands simultaneously.

SSID

The Service Set Identifier (SSID) is the name assigned to a wireless network.

Examples:

Users select the SSID when connecting to a wireless network.

Changing the default SSID can make network identification easier, although it does not improve security by itself.

Wireless Security

Wireless networks must be protected because radio signals can extend beyond the physical building.

Without security, unauthorized users may gain access to the network.

WEP (Wired Equivalent Privacy)

WEP was the first widely used Wi-Fi security protocol.

Characteristics:

Modern networks should not use WEP.

WPA (Wi-Fi Protected Access)

WPA improved wireless security over WEP.

Improvements included:

Although stronger than WEP, WPA has also become outdated.

WPA2

WPA2 became the industry standard for many years.

Features include:

Many networks still use WPA2 successfully.

WPA3

WPA3 is the newest Wi-Fi security standard.

Benefits include:

Whenever possible, WPA3 should be used.

Strong Wireless Security Practices

Protect wireless networks by:

These practices significantly improve wireless security.

Bluetooth

Bluetooth is a short-range wireless technology used to connect personal devices.

Common Bluetooth devices include:

Bluetooth is designed for low-power, short-distance communication.

Bluetooth Characteristics

Bluetooth typically provides:

Bluetooth is commonly associated with Personal Area Networks (PANs).

Near Field Communication (NFC)

Near Field Communication (NFC) enables wireless communication over extremely short distances.

Typical uses include:

NFC usually operates within a few centimeters.

Cellular Networks

Cellular networks provide wireless communication over large geographic areas using cellular towers.

They enable:

Cellular networks support mobile users beyond the range of Wi-Fi.

4G

Fourth-generation (4G) cellular technology provides:

4G greatly improved mobile Internet performance over previous generations.

5G

Fifth-generation (5G) cellular technology offers:

5G is designed to support modern applications requiring fast and responsive wireless communication.

Internet of Things (IoT)

The Internet of Things (IoT) refers to physical devices connected to the Internet that can collect, exchange, and sometimes act on data.

Examples include:

IoT devices increase convenience but also introduce additional security considerations.

Virtual Private Network (VPN)

A Virtual Private Network (VPN) creates an encrypted connection over an untrusted network, such as the Internet.

A VPN helps protect data while it travels between a user’s device and a remote network.

Benefits of a VPN

VPNs provide:

VPNs are commonly used by businesses to allow employees to securely access internal resources from remote locations.

Common Network Problems

Networks may experience a variety of issues.

Common problems include:

Recognizing these issues is the first step in effective troubleshooting.

Basic Network Troubleshooting Process

A systematic troubleshooting approach improves efficiency.

Typical steps include:

  1. Identify the problem.
  2. Gather information.
  3. Check physical connections.
  4. Verify network settings.
  5. Restart affected devices.
  6. Test connectivity.
  7. Isolate the issue.
  8. Implement a solution.
  9. Verify normal operation.
  10. Document the resolution.

Following a structured process helps avoid overlooking simple causes.

Troubleshooting Tools

Common tools used to diagnose network issues include:

These utilities are valuable for identifying connectivity and configuration problems.

Factors Affecting Network Performance

Several factors influence network speed and reliability.

These include:

Understanding these factors helps identify performance bottlenecks.

Improving Network Performance

Performance can often be improved by:

Best Practices

Key Terms

Exam Tips

Network Models, Cloud Networking, Network Security, and Documentation

Client-Server Networks

A client-server network is a network model in which dedicated servers provide resources and services to client devices.

A server is a powerful computer that stores data, runs applications, or manages network resources.

A client is a computer or device that requests services from the server.

Examples include:

Most business networks use the client-server model because it provides centralized management and improved security.

Advantages of Client-Server Networks

Benefits include:

Client-server networks are ideal for organizations with many users and devices.

Disadvantages of Client-Server Networks

Some disadvantages include:

Peer-to-Peer (P2P) Networks

A peer-to-peer (P2P) network allows devices to communicate directly without relying on a dedicated server.

Each device can function as both a client and a server.

Examples include:

P2P networks are simple and inexpensive but become difficult to manage as the number of devices increases.

Advantages of Peer-to-Peer Networks

Benefits include:

Disadvantages of Peer-to-Peer Networks

Limitations include:

Client-Server vs. Peer-to-Peer
Client-ServerPeer-to-Peer
Dedicated serverNo dedicated server
Centralized managementDistributed management
Better securityLimited security
Highly scalableBest for small networks
Easier backupsManual backups
Higher costLower cost
Cloud Networking

Cloud networking refers to using cloud-based infrastructure to provide networking services and connectivity.

Instead of relying entirely on physical hardware, organizations can deploy networking resources in cloud environments.

Cloud networking supports:

Cloud networking enables organizations to scale quickly while reducing hardware requirements.

Cloud Computing Service Models

Networking often supports cloud service models such as:

Infrastructure as a Service (IaaS)

The provider supplies virtualized infrastructure, including:

Customers manage the operating systems and applications.

Platform as a Service (PaaS)

The provider manages:

Customers focus on developing and deploying applications.

Software as a Service (SaaS)

The provider delivers complete software applications over the Internet.

Examples include:

Users simply access the application through a web browser or client application.

Virtualization

Virtualization allows multiple virtual machines (VMs) to run on a single physical computer.

Each virtual machine operates as though it were an independent computer.

Advantages include:

Virtualization is a key technology supporting cloud computing.

Network Security

Network security protects systems, devices, and data from unauthorized access, attacks, and other threats.

A layered security approach provides the strongest protection.

Common Network Security Threats

Networks may be exposed to:

Understanding these threats helps organizations implement appropriate defenses.

Authentication

Authentication verifies the identity of a user or device before granting access to network resources.

Common authentication methods include:

Strong authentication significantly improves network security.

Authorization

After authentication, authorization determines what resources an authenticated user is allowed to access.

Authorization controls:

Following the Principle of Least Privilege (PoLP) ensures users receive only the permissions required for their responsibilities.

Encryption

Encryption protects data by converting it into unreadable ciphertext.

Only authorized users with the correct decryption key can restore the original information.

Encryption protects:

Encryption helps maintain confidentiality and data privacy.

Multi-Factor Authentication (MFA)

Multi-Factor Authentication (MFA) requires users to provide two or more independent forms of verification.

Authentication factors include:

Something You Know

Examples:

Something You Have

Examples:

Something You Are

Examples:

MFA greatly reduces the risk of unauthorized account access.

Access Control

Access control determines who may access network resources and what actions they may perform.

Examples include:

Proper access control reduces security risks.

Network Monitoring

Continuous monitoring helps identify performance problems and security threats before they become serious.

Administrators monitor:

Monitoring supports proactive network management.

Network Documentation

Good documentation is essential for managing and troubleshooting networks.

Typical documentation includes:

Accurate documentation simplifies maintenance and disaster recovery.

Disaster Recovery

A disaster recovery plan (DRP) outlines procedures for restoring network operations after major failures.

Potential disasters include:

An effective DRP minimizes downtime and supports business continuity.

Business Continuity

Business continuity ensures critical business operations continue during and after disruptions.

Business continuity planning includes:

Organizations that prepare in advance recover more quickly from unexpected events.

Best Practices

Follow these networking best practices:

Key Terms

Exam Tips

Networking Fundamentals

TCP/IP and Protocols

Wireless Networking

Network Security

Cloud Networking