Transcript Networks - Washtenaw Community College

Networks
CPS120
Introduction to Computer Programming
Lecture 4
What Is a Network
A network is a group of connected
computers that allow people to share
information and equipment
Types of Networks
LAN (Local Area Network) connects
computers within a small geographic area like
a building
WAN (Wide Area Network) connects
computers across a large geographic area
like a city or country (often via satellite)
Internet: World-wide network of networks
Advantages
Road warriors
Eliminate “sneakernet”
Share information
Share equipment
Who Runs It?
A network administrator manages the
network and makes sure it runs
smoothly

Often called a systems administrator or an
IS manager
Network Applications
Electronic mail
Groupware
Calendaring
 Scheduling

Video-conferencing

Requires sound card, speakers, mike &
camera
Physical Networking
Hubs

A hub is a device that provides a central location
where all the cables on a network come together
NICs (Network Interface Card)

An expansion card that physically connects each
computer to the network
Cables
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Coaxial, Unshielded Twisted Pair (UTP), Shielded
Twisted Pair, Fiber-optic
Wireless
How Information Is
Stored
Client-Server:

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Used for large networks
Files are stored on a central computer and
everyone who can access the network can be
given access them
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Easy to create scheme to backup and protect files
Client: a computer that can access information
stored on the server
Server: Central computer that stores files
NetWare, UNIX, Windows NT/2000
How Information Is
Stored
Peer-to-Peer:
Used for a small number of computes (e.g.
10)
 Files stored on own computers; access
given to them to others on the network
 LANtastic, Windows-98, Windows-ME

How Information Is
Exchanged
Ethernet:
Most popular and least expensive solution
 Each computer waits for a pause before
sending information

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Collisions between information often occur


Like polite conversation
Computers wait a moment, then resend
Ethernet – 10 Mbps, Fast Ethernet – 100
Mbps, Gigabit Ethernet 1000 Mbps
How Information Is
Exchanged
Token-ring is a type of network where a token
that collects and delivers information is
passed from compute to computer

Speeds of 4 or 16 Mbps
Asynchronous Transfer Mode (ATM) is a type
of network that works by sending information
in equal-sized pieces called cells

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25, 155, 622 or 2488 Mbps
Often networks networks
Network Security
Operating System Security

Other system software
Firewall – specialized hardware or software
package designed to protect a private
computer network from unauthorized access

Think “Moat”
User name and password

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Used for authentication
Good passwords
Intranet
Small version of the Internet in a
company
Uses familiar web-browsers and email
packages
Allows hyper-linking
VPNs (Virtual Private Network)
End-to-end encryption
 More cost efficient than private lines

Internet and WWW
Chapter 10
Internet Fundamentals
Dates from DARPA in the 1960s
Consists of thousands of connected networks
around the world

Each organization on the Internet is responsible
for maintaining its own equipment

These organizations allow you to pass-through their nets
Designed to provide multiple routing to
bypass disabled computers
Called cyber-space or the information
superhighway
Internet Offerings
Electronic mail (Most popular application)
Information
Entertainment
Discussion Groups
Chat
Programs (Shareware)
Online shopping
Connecting
Computer
Software
Modem or high-speed connection
ISP (Internet Service Provider)

Access for a fee
World Wide Web
Part of the Internet consisting of a huge
collection of documents stored on computers
around the world

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Web server: computer that stores and delivers
web pages
Web site: collection of web pages

URL (Uniform Resource Locator) – unique address

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HTTP, Computer, Directory, Name of Page
Hyperlinks jump to different web pages
Browsers
A program that lets you view and navigate
information on the World Wide Web

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Home Page: Web page that appears each time
you start your web browser
Browser:
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Internet Explorer
Netscape Navigator
Features

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Bookmark
History lists
Multimedia
MP3 – compressed files containing music or
video

WinAmp
Streaming video – requires player

RealPlayer, QuickTime
Enhancements
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Java
JavaScript
ActiveX
Web Portal
Central starting point for browsing
personalized by the individual
Yahoo, Excite, Go, Lycos
 Info
 Free services like email, shopping, chat,
games, stock quotes and sports scores

Shopping
Auctions
Secure web sites – i.e. HTTPS
Children on the Web
Inappropriate information

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Pictures
Documents
Protection

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Adult supervision
Browser restrictions
Restriction programs
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CyberPatrol
NetNanny
Create & Publish Web
Pages
HyperText Mark-up Language is a computer
code used to create Web pages
There are many programs available, called
visual editors which can help you create Web
pages without having to learn HTML
Publishing your pages – loaded to an
addressable server