DATA COMMUNICATION AND NETWORKING.

 Introduction to Data Communication.
 Introduction to Computer Networks
DATA COMMUNICATION AND COMPUTER NETWORK
DATA COMMUNICATION
Define data communication.
 Data communication is the process of sharing ideas, information and message with others
in a particular time and place.
 It is the exchange of data from one point to another.
ELEMENTS OF DATA COMMUNICATION
 Sender
 Receiver
 Message
 Transmission media
 Protocol
SENDER: The person intending to transmit information.
RECEIVER: Is that to whom the information is to be delivered.
TRANSMISION MEDIA: This is the Chanel through which the information /data will
have to flow through.
PROTOCOL: Is the standard method of transferring data between different computers.
 A set of rules that govern the transfer of information.
DATA COMMUNICATION TOOLS
 These are items that aid the transfer/exchange of data from one point to another.
TYPES OF DATA COMMUNICATION TOOLS
 Manual data communication tools
 Electronic data communication tools
TYPES OF MANUAL DATA COMMUNICATION TOOLS
 Drum
 Bell
 Messengers
 Trumpet
TYPES OF ELECTRONIC DATA COMMUNICATION TOOLS
37ICT lesson
Computer
 Mobile phones
 Internet
 Radio
 Email
 Skype
 Instant messaging
 Satellite
PHYSICAL TRANSMISSION MEDIA
 Is that which use wire cables and other physical materials to send communication signals.
WIRELESS TRANSMISSION MEDIA
 Is that which send communication signals through the air or space using radio ,
microwave and infrared signals.
EXAMPLES OF PHYSICAL TRANSMISSION MEDIA
 Two or more computers connected over a network using wires.
 A messenger taking letter (information) from one place to another
EXAMPLES OF WIRELESS TRANSMISSION MEDIA
 Bluetooth
 Broadcast radio
 Internet
SERVICES OFFERED BY DATA COMMUNICATION TOOLS
 Chart
 Video call
 Audio call
TYPES/KINDS OF PHYSICAL TRANSMISSION MEDIA
 Twisted pair wire
 Coaxial cable
TYPES/KINDS OF WIRELESS TRANSMISSION MEDIA
 Microwave
 Satellite
APLICATION OF DATA COMMUNICATION
 Information service
 Telephone
 Telegraph
 Fax
38ICT lesson
omosoft Technology
 Video text
 Tele text
METHODS OF DATA TRANSIMISSION
 Synchronous transmission.
 A synchronous transmission
COMPUTER NETWORK
 This is a group of computers connected together in order to share data and resources.
REQUIR MENTS FOR SETTING UP COMPUTER NETWORK
 Router
 Transmission media
 Modem
 Network software e.g. Window internet explorer.
ROUTER: A device that works like abridge but is able to select the best route from
network based on traffic load.
MODEM: Is a device that converts the computer digital signals into analog signals.
POSITIVE IMPLICATIONS OF COMPUTER NETWORK
 Sharing data/information between two or more parties on the network.
 Sharing hardware e.g. Printer.
 Sharing computer software
 Centralizing administration and support for security Facilitate communication via
email.
 Sharing data and information stored on the computers onto network
NEGATIVES IMPLICATION OF COMPUTER NETWORK
 The hardware, software and expertise may be required to setup a network can be
expensive.
 Networks are vulnerable to security threat e.g. hackers can distort information.
 If the server fails to work, the complete network may also fail to work.
TYPES OF NETWORK
 LAN (Local Area Network)
 WAN (Wide Area Network)
 MAN (Metropolitan network)
LAN: Is a network that covers limited distance (2km) such as school computer laboratory, an
office or a group of closely positioned building to allow computer to share information and
resources.
CHARACTERISTIC OF LAN (Local Area Network)
 Physically limited (less than 2km)
 High band width(greater than 1mbps)
 In expensive cables media(coax and twisted pair)
39ICT lesson
 Data and hardware sharing between users owned by the user. MAN: This is a network
that connects two or more LANS e.g. AAU network located in Addis Ababa, Ethiopia
which inter connect the different faculty in the city.
WAN: this is the network that spans a large geographical area.
 The network is connected by means of telephones lines, ISDN (Integrated Service Digital
Network) like radio wave or satellite link.
NETWORK MODELS
These include:
 Peer to peer
 Client to server
CLIENT –SERVER: This is a network in which one or more computers are designed of server
and the others on the network of client.
PEER-PEER: is a network which lacks a dedicated server every computer act as both client and
server.
Define
a) SERVER: A computer that provide shared resources to network users.
b) CLIENT: A computer that access shared network resources provided by the
server.
c) RESOURCES: any devices or services such as file, printers or other items
made available for use by members of the network.
FACTORS TO
CONSIDER WHEN CHOOSING ANETWORK MODE
 Size of the organization.
 Type of the business.
 Amount of network traffic.
 Level of security required.
 Level of administrative support available.
 Need of the network us
Internet and World Wide Web.
 Introduction to the Internet. Internet Services.
 World Wide Web
Define the term internet
Internet is a collection of networks linked together that all use TCP/IP protocols. An internet
(with lowercase i) is any computer connected to each others and are not part of the Internet
unless they use TPC/IP protocols.
What are the implication of internet
The implication of internet refers to the advantages and dis advantages of using internet which
are listed below
Advantages of internet
It can allow video conferencing e.g. by using skpe.
Help in making friendship and love e.g. by using face book
It help us for research e.g. by using www. Google.com

News, of all kinds is available almost instantaneously.
The internet provides the ability of emails. Free mail service to anyone in the country
and across the globe.
Provides jobs to people who want to make money online like buy and sell services,
blogs and web design.
Abundant Information Resources
Faster Communication
Entertainment for Everyone
Online Services and E-commerce
Dis advantages of internet
There is a lot of wrong information on the internet. Anyone can post anything, and much of
it is garbage.
Pornography that can get in the hands of young children too easily.
Hackers can create viruses that can get into your personal computer and ruin valuable
data.
Hackers can use the internet for identity theft.
Spamming
Malware Threats
Identify the different internet communication services you know
• Instant messaging
• Chat rooms
• Email
• File transfers
• News groups
• Peer to peer networks
• Forums
Group assignment
1. Describe how you could use email services to communicate with a friend
2. Explain how you could use internet to carry out research on computer about importance of
computer in our education system.
Explain the concept of netiquette

 Netiquette” is network etiquette, the do’s and don’ts of online communication
 Netiquette covers both common courtesy online and the informal “rules of the road” of
cyberspace. This page provides links to both summary and detail information about
Netiquette for your browsing pleasure.
 Netiquette, or net etiquette, refers to etiquette on the Internet. Good netiquette involves
respecting others’ privacy and not doing anything online that will annoy or frustrate other
people. Three areas where good netiquette is highly stressed are e-mail, online chat, and
newsgroups. For example,
people that spam other users with unwanted e-mails or flood them with messages have
very bad netiquette. You don’t want to be one of those people. If you’re new to a
newsgroup or online chat room, it may help to
observe how people communicate with each other before jumping in.
Define a web browser
A web browser is a soft ware program used to access and view web pages
Identify different web browser
Example of web browsers
 Microsoft internet explorer
 Google chrome
 Netscape navigator
 Mozilla Firefox
 Safari
 Opera Mini
Define search engine
 Search engine is a software program that can be used that can be used to find web sites,
web pages and files on internet
Learner’s activities
1. Identify different search engines
2. Search for information about HIV virus from the web
3. use search engine syntax
Define a web site
A Website is a collection of Web Pages. A Web Page is an Internet document that is
displayed within the Internet browser window.
Identify different examples of web site
 www.dstv.com
 www.bbcworld.com
 www.google.com
 www.yahoo.com
Explain the concept of cloud computing
 Cloud computing is a general term for anything that involves delivering hosted services
over the Internet.
 The practice of storing regularly used computer data on multiple servers that can be
accessed through the Internet.
Internet domain
System Security, ICT Ethical Issues and Emerging Technologies.
 Computer System Security.
 Privacy and ICT Ethical Issues.
 Emerging Technologies.
ICT industry
Major Features of the Internet
The World Wide Web
• E-Mail
• News
• Telnet
• File Transfer Protocol (FTP)
• Internet Relay Chat (IRC)
Major Features of the Internet

-The World Wide Web
• The World Wide Web is a part of the Internet, which supports hypertext documents,
allowing users to view and navigate different types of data.
• A Web page is a document encoded with hypertext markup language (HTML) tags.
• HTML allows designers to link content together via hyperlinks.
• Every Web page has an address, a Uniform Resource Locator (URL).

Electronic mail (e-mail) is the most popular reason
peopleuse the Internet.
• To create, send, and receive e-mail messages, you need an e-mail program and an
account on an Internet mail server with a domain name.
• To use e-mail, a user must have an e-mail address, which you create by adding your user
name to the
e-mail server’s domain name, as in jsmith@aol.com.

 Telnet
• Telnet is a specialized service that lets you use one computer to access the contents of
another computer – a Telnet host.
• A Telnet program creates a “window” into the host
so you can access files, issue
commands, and exchange data.
• Telnet is widely used by libraries, to allow visitors to look up information, find articles,
and so on.
• To Start Internet Explorer
• Click Start > Programs > Internet Explorer
• Or Double-click the Internet Explorer icon on the Desktop

E-mail
• Mail sent or received with the help of an electronic device such as a computer is called
electronic mail or e-mail.
• Advantages of E-mail
• E-mail is delivered almost instantaneously.
• The e-mail is sure to be delivered provided the e-mail address is correct.
• E-mail is much cheaper than the regular postal service.
• E-mail can be accessed from any computer having an Internet connection.
• E-mail helps you keep in touch with your friends even after they have changed their
residence.
Website Addresses Or URL
To view the contents of a website you need to know the website address also called the
uniform resource locator (URL) for e.g. www.dstv.com, www.bbcworld.com
What are some services found on the Internet?
1.E-mail
2.Web
3.File transfer
4.Chat
5.Message board
6.Instant messaging What is a URL?
Unique address for a web page
 A web server delivers the Web page to your computer What is a hyperlink (link)?
Build in connection to another related web page
 Item found elsewhere on same Web page
 Different Web page at same Web site
 Web page at a different Web site
What is a search engine?
 Program used to find Web sites and Web pages by entering words or phrases called
search text

Examples of search engine

1. Google. Google Search Engine is the best search engine in the world and it is also one of most popular products from Google. …
2. Bing. Bing is Microsoft’s answer to Google and it was launched in 2009. …
3. Yahoo. …
4. Baidu. …
5. AOL. …
6. Ask.com. …
7. Excite. …
8. DuckDuckGo.