This document is a lesson on network fundamentals that describes networks, their benefits and risks. It defines key network terms and outlines different network types including local area networks (LANs) and wide area networks (WANs). The lesson discusses client/server networks and peer-to-peer networks. It also covers network communication hardware, security issues and planning for security on networks.

1. 1
Lesson 24
Network Fundamentals
Computer Literacy
BASICS: A
Comprehensive Guide
to IC3, 3rd Edition
Morrison / Wells

2. Lesson 24
Objectives
 Describe a network.
 Explain the benefits of a network.
 Identify the risks of network computing.
 Describe the roles of clients and servers on a network.
 List and describe the types of networks.
 List and describe communications media and
hardware.
 Describe network security.
2 Morrison / Wells CLB: A Comp Guide to IC3 3E

3. Lesson 24
Vocabulary
 biometric security
measures
 cable modem
 client
 client/server network
 communication
channels
 digital subscriber line
(DSL)
 extranet
 firewall
 hacker
 hub
 Internet
 intranet
 local area network (LAN)
 modem
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4. Lesson 24
Vocabulary (continued)
 node
 peer-to-peer network
 proxy server
 Public Switched
Telephone Network
(PSTN)
 router
 server
 server operating system
 T-1 line
 wide area network (WAN)
 WiMAX
 wireless Internet service
provider
 (WISP)
 wireless LAN (WLAN)
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5. Lesson 24
Introduction
 Connecting computers through a network, a
group of two or more computers linked together,
allows users to share software applications and
to share hardware devices such as printers,
scanners, and other hardware add-ons.
 Companies and organizations use networks to
connect employees and subsidiaries nationally
and even internationally.
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6. Lesson 24
Introducing Networks
 The Public Switched
Telephone Network
(PSTN) supports
telephone service
and is the world’s
collection of
interconnected
commercial and
government-owned
voice-oriented
systems.
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7. Lesson 24
Network Benefits
 The biggest network of all is the Internet.
Network benefits include:
– Information sharing
– Collaborative environment
– Hardware sharing
– Software sharing
– Enhanced communications
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Information sharing

8. Lesson 24
Risks of Networked Computing
 As with any technology, disadvantages also
exist. Disadvantages of networks include:
– Individual loss of autonomy
– Malicious code
– Network faults
– Setup and management costs
– E-mail is not necessarily private
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9. Lesson 24
Client/Server Networks
 The term client/server network describes a software
architectural model relationship.
 In most instances, the client is a software program such
as Internet Explorer. The server is hardware and can be
one of many types of servers, such as a mail server, a
database server, an FTP server, an application server, or
a Web server.
 Server operating systems are high-end programs
designed to provide network control and include special
functions for connecting computers and other devices into
a network.
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10. Lesson 24
Network Types
 Networks are divided into two main types:
local area networks (LANs) and wide area
networks (WANs).
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11. Lesson 24
Network Types (continued)
 Local Area Networks:
 Most LANs connect
personal computers,
workstations, and other
devices such as
printers and scanners
in a limited
geographical area.
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Wireless LAN

12. Lesson 24
Network Types (continued)
 Wide Area Networks:
 A WAN covers a large geographical area and can contain
communication links across metropolitan, regional, or national
boundaries.
 Network types include:
– Client/server network: Server manages resources
– Peer-to-peer network: All computers are equal
– Intranet: Used within an organization
– Extranet: Specific outside users can access
– Internet: Global network allows worldwide connection
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13. Lesson 24
Network Communications
 Communication Hardware:
 Communication hardware devices facilitate the
transmitting and receiving of data. Examples are:
– Modem: Converts analog signals to digital and vice
versa
– Cable modem: Uses coaxial cable
– Digital subscriber line: Uses ordinary phone lines
– T-1: Type of fiber-optic telephone line
– Wireless: Delivers fast connection speeds
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14. Lesson 24
Network Security Issues
 Passwords are the
most common form
of restricting access
to data.
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 Establishing and maintaining computer security is
necessary to keep hardware, software, and data
safe from harm or destruction.

15. Lesson 24
Network Security Issues
(continued)
 Other security measures include:
– Electronic identification cards
– Firewalls to protect companies’ networks from
external networks
– Antivirus software
– A proxy server that acts as an intermediary
between a user and the Internet.
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16. Lesson 24
Network Security Issues
(continued)
 Planning for Security:
 Companies must plan for security before it is
needed
– Institute a selective hiring process.
– Regularly back up data and store it off site.
– Employ biometric security measures.
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17. Lesson 24
Network Security Issues
(continued)
 Wireless Security:
 Wireless networking
is very common, but
has many security
issues and hackers
have found it very
easy to access
wireless networks.
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18. Lesson 24
Summary
In this lesson, you learned:
 A network is a group of two or more computers
linked together.
 A telephone network is similar in makeup to a
computer network. The Public Switched
Telephone Network (PSTN) supports telephone
service, and it is the world’s largest collection of
interconnected commercial and government-owned
voice-oriented systems.
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19. Lesson 24
Summary (continued)
 You can use a network for information sharing,
hardware sharing, software sharing, and as a
collaborative environment.
 Networks are divided into two main types: local area
networks and wide area networks.
 Local area networks (LANs) connect personal
computers, workstations, and other devices such as
printers and scanners in a limited geographical area,
such as an office building, a school, or a home.
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Morrison / Wells CLB: A Comp Guide to IC3 3E

20. Lesson 24
Summary (continued)
 A wide area network (WAN) is made up of several
connected local area networks.
 In a client/server network, one or more computers
on the network act as a server. The server
manages network resources. In a peer-to-peer
network, all of the computers are equal. No
computer is designated as the server. People on
the network each determine what files on their
computer they share with others on the network.
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21. Lesson 24
Summary (continued)
 Data security is a risk with many networks. Some
risks to computers are natural causes, some are
accidents, and others are intentional.
 The best way to protect data is to effectively control
the access to it. Generally, this protection is the
responsibility of the network administrators and
security personnel. If unauthorized persons gain
access to data, they may obtain valuable information
or trade secrets. Hackers are people who break into
computer systems to steal services and information.
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22. Lesson 24
Summary (continued)
 Transmission media can be either physical or
wireless.
 A modem is a type of communication device.
A hub is a device that controls the incoming
and forwarding of data. A router directs traffic
on the Internet or on multiple connected
networks.
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