- The idea of ARPANET, one of the earliest computer networks, was proposed by Leonard Kleinrock in 1961, in his paper titled “Information Flow in Large Communication Nets.“
- This has gone through numerous developments
- The Wi-Fi Alliance introduced WPA3 encryption for Wi-Fi in January 2018, which includes security enhancements over WPA2
What is a Computer Network?
- A system containing any combination of computers, computer terminals, printers, audio or visual display devices, or telephones interconnected by telecommunication equipment or cables: used to transmit or receive information.
- Though laudable, it normally comes with its associated problems including sharing of virus, having access to several illicit materials among others
Types of Network
- There are many types of computer networking which are used world wide these days.
1.LAN – Local Area Network
2.WAN – Wide Area Network
3.WLAN – Wireless Local Area Network
4.PAN – Personal Area Network
5.SAN – Storage Area Network
6.GAN – Global Area Network
7.MAN – Metropolitan Area Network
8.CAN – Controller Area Network
9.DAN – Desk Area Network
10.VPN – Virtual Private Network
Distinguishing between LAN,WAN,MAN
Network Classification by their Component Role
Peer to Peer Network
- In peer to peer network each computer is responsible for making its own resources available to other computers on the network.
- Each computer is responsible for setting up and maintaining its own security for these resources.
- Also each computer is responsible for accessing the required network resources from peer to peer relationships.
- Peer to peer network is useful for a small network containing less than 10 computers on a single LAN .
- In peer to peer network each computer can function as both client and server.
- Peer to peer networks do not have a central control system. There are no servers in peer networks.
- Peer networks are amplified into home group.
Advantages & Disadvantages of Peer to Peer Network
1.Use less expensive computer hardware
2.Easy to administer
3.No Network Operating System required
4.More built in redundancy
5.Easy setup & low cost
1.Not very secure
2.No central point of storage or file archiving
3.Additional load on computer because of resource sharing
4.Hard to maintain version control
- In client-server network relationships, certain computers act as server and other act as clients. A server is simply a computer, that available in the network resources and provides service to other computers when they request it. A client is the computer running a program that requests the service from a server.
- Local area network(LAN) is based on client server network relationship.
- A client-server network is one on which all available network resources such as files, directories, applications and shared devices, are centrally managed and hosted and then are accessed by client.
- Client serve network are defined by the presence of servers on a network that provide security and administration of the network.
Advantages and Disadvantages of Client/Server Network
- Very secure
- Better performance
- Centralized backup
- very reliable
- Requires professional administration
- More hardware intensive
- More software intensive
- Expensive dedicated software
Types of Servers
File Server: These servers provide the services for storing, retrieving and moving the data. A user can read, write, exchange and manage the files with the help of file servers.
Printer Server: The printer server is used for controlling and managing printing on the network. It also offers the fax service to the network users.
Application Server: The expensive software and additional computing power can be shared by the computers in a network with he help of application servers.
Message Server: It is used to co-ordinate the interaction between users, documents and applications. The data can be used in the for of audio, video, binary, text or graphics.
Database Server: It is a type of application server
Applications of Computer Network :
- Sharing of resources such as printers
- Sharing of expensive software’s and database
- Communication from one computer to another computer
- Exchange of data and information among users via network
- Sharing of information over geographically wide areas.
Components of Computer Network
- Cables as links between the computers
- A Network Interfacing Card (NIC) on each computer
- Software called operating system(OS)
- Modem: is a device that converts analogue signals to digital and digital signals to analogue so that a computer can send and receive data over a telephone system
- Switch: is a device used to send packets of data between components of a network.
- NIC: enables microcomputers to send and receive messages over a cable network.
- Router: is a special networking device that directs communication message when several networks are connected together.
1.10Base5 (Thick Coaxial) Cable – uses a 15-pin D-shaped connectors
2.10Base2 (Thin Coaxial) Cable – uses a BNC T-connector.
3.10BaseT (Shielded Twisted Pair [UTP]) Cable – uses an RJ-45 connector for fast Ethernet connection.
4.10BaseFL and 100BaseFX (Optical Fiber or Fiber-Optic) cable – uses ST or SC Fiber-optic connector.
- The network provided to the users can be divided into two categories:
- Types of resources are:
- Hardware: A network allows users to share many hardware devices such as printers , modems, fax machines, CD ROM, players, etc.
- Software: sharing software resources reduces the cost of software installation, saves space on hard disk.
Other Benefits of Computer Network
- Increased Speed
- Reduced Cost
- Improved Security
- Centralized Software Managements
- Electronic Mail
- Flexible Access
Disadvantages of Computer Networks
- High Cost of installation
- Requires Time for Administration
- Failure of Server
- Cable Faults
What is Internet
- The Internet is a worldwide system of computers joined by a common set of networking and software protocols.
- Each computer in this global system of computers has its own unique address – the Internet Protocol (IP) address.
What makes the Internet Useful?
- Send and receive messages from friends and relations using the Electronic Mail (E-Mail)
- Search for jobs/ Apply for jobs on-line
- Plan a career
- Apply for grants for research
- Read National and International Newspapers and Magazines
- Listen to Radio Broadcasts
- Learn how to write good curriculum vitae
- Send Pictures to others
- Do Banking Online
- Buy and Sell
- Earn a Diploma or Degree Online
- Register for University courses.
- Visit Libraries to make references and even print particular pages of a required material
- Chat with Friends or hold conferences with others in different parts of the world.
- Look for pen pals
How the Internet Works
- When you request or send information such as a webpage or email, the computer breaks the request into smaller, more manageable pieces called packets.
- Each of these packets contains both the sender’s Internet address and the receiver’s address.
- Every packet is sent first to a gateway computer that understands a small portion of the Internet.
- This gateway computer reads the destination address and forwards the packet to an adjacent gateway, closer to the packets destination.
- This will in turn read the destination address and so forth across the Internet until a gateway recognizes the packet as belonging to a computer within its immediate neighborhood or domain.
- Regardless of what operating system you use (Mac, PC, or UNIX) to connect to the Internet, the computers all basically speak the same language, which allows computers to exchange information with other computers next door or across the planet.
- A message is divided into numerous packets. Each packet is sent by a different route across the Internet.
- Internet Protocol (IP) delivers the packets. Packets can arrive in a different order they were sent.
- The Transmission Control Protocol (TCP) has the job of putting them back in the right order.
Connecting to the Internet
The most commonly used is a Dial-up Connection
- Less Costly
- Need a Standard Phone Line
- Internet is accessed by dialing a telephone number into a service provider using a modem cable connected to RJ-11
- Broadband access may require additional hardware and software provided by your ISP.
- Broadband connections offer faster means to connect to the internet.
ii.Digital Subscriber Line (DSL)
iv. Other Services
Cable Internet Connection
- Uses coaxial cable and a cable modem
- Data speeds received is up to 4Mbps
- Data speeds sent is up to 500Kbps
- Connection can be slowed by the number of users connected at any one time.
Digital Subscriber Line (DSL)
- DSL uses a standard phone line to connect to the internet.
- The line is split between digital and voice
- This means that the digital signal does not have to be converted into sounds so that greater speeds can be realized.
- You need a satellite dish, which is placed outside your home and connect to your computer with coaxial cable.
- Its initial equipment investment is high.
- Though bandwidth can be high, the signal must travel a long distance from the satellite and back. This increases the delay time.
ISP (Internet Service Provider)
- An ISP is a company that collects a monthly or yearly fee in exchange for providing the subscriber with Internet access.
- An ISP might provide internet connection through
iii.DSL (Digital Subscriber Line or Dedicated Service Line)
iv.Other types of Internet access.
- Is a software installed on a computer system that allows you to locate, view and navigate the web.
i.Microsoft Internet Explorer
- Open a browser to show the toolbars
- Internet Address is a unique address which links up to a web page.
- It is known as Uniform Resource Locator (URL)
- A typical address http://www.myjoyonline.com/politics
- http is the protocol which identifies the means of access
- myjoyonline is the domain name contains the host and top level domain
- politics, identifies the sub directories within the website.
- Sending messages through electronic means without the use of papers.
1.Very fast in delivery messages
2.Messages can be sent anytime
3.It works 24 hours in seven days
4.Copy of your messages are always available
5.It is cheap
6.Can be delivered to a number of recipients
7.Files, graphics and images can be sent.
Components of an E-Mail Address
- Consider this email@example.com
- okakomenco is the local part, which is the name of the mailbox on the destination computer
- outlook is the mail server where the mailbox “okakomenco” exists.
- .com is the type of organization on the internet which is hosting the mail server.
What is www?
- The part of the internet that makes use of graphical software (web browsers, HTML) to display content.
- www is a subset of the internet
Locating and using Information from different Sources
Searching for Information on the Internet
- Search Engine: is a set of programs that searches the web for specific keywords you wish to query and then returns a list of the web sites on which those keywords are found.
- Search engine has a program called a spider which collects data on the web.
- An indexer program organizes the data into a large database.
- Search engine software searches the indexed data, pulling out relevant information according to your search.
- Search engines includes Google, Metacrawler, AltaVista, Lycos, Excite, Yahoo, Overture, Woyaa, etc.
Tips for Searching
- Each search engine help section offers detailed options.
- Use only lower case letters to enter your search criteria
- Use quotation marks to search for an exact phrase
- Do not use global searching eg. “weather reports” will give you weather report in the US or the World. However, “weather report Africa” is much more likely to give you the information you are searching if your concern is on Africa.
- The information gathered is
Use of Directory
- A directory is a guide to the internet organized by topics and subtopics.
- After selecting the main subject from the directory, you narrow your search by successively clicking on subfolders that match your search until you have reached the appropriate information.
- To find previews on newly released movies in yahoo’s subject directory, you would click on the main category of Entertainment, select the subcategory Movies and Films, select the further subcategory Preview and then open one of the listed Web sites.
- Social Networking
- Weblogs/Blogs: they are ways people post their thoughts for public viewing.
File Transfer Protocol [FTP]
- Internet utility software used to upload and download files.
- It gives access to directories or folders on remote computers
- Allows software, data and text files to be transferred between different kinds of computers.
What is Information Literacy?
- According to the American Library Association, “Information literacy is a set of abilities requiring individuals to ‘recognize when information is needed and have the ability to locate, evaluate, and use effectively the needed information.”
- “Information Literacy empowers people in all walks of life to seek, evaluate, use and create information effectively to achieve their personal, social, occupational and educational goals. It is a basic human right in a digital world and promotes social inclusion in all nations.”
Information Retrieval Tools
- Information Retrieval Tools aid the library user to locate, retrieve and use the needed Information in various formats. These Information retrieval tools are bibliography, index and abstract, shelve lists, Online Public Access Catalogue (OPAC) and library card catalogue.
- According to Bell (1997), electronic resources embrace Information Technology (IT), electronic publishing, digital, virtual or electronic libraries, bibliographic and full-text data (including journals) in electronic form, On- line Public access Catalogues (OPAC), World Wide Web pages, discussion lists, and electronic .
- Library Catalog.
- Copyright is a set of utmost rights granted by the law of a jurisdiction to the author or creator of an original work, including the right to copy, distribute and adapt the work.
Copyright Issues in ICT
- There are four main areas where copyright issues occur in ICT, they are:
4.Computer generated works
ICT Tools and Health Issues
- Computers are an essential tool in the work of most organizations. Although problems can occur through their use, with the proper equipment, ergonomic design, proper techniques and working practices, the risk of problems can be greatly reduced
- Explain the following terms as best as you can. (not more than 3 sentences each)
iv. Search Engine
- Make 3 sentences to show how the following tools can help in information retrieval
3.Electronic resources/TESSA OER (Online, Databases, Internet, MOOCS, CD-ROM)
4.Reference sources (Almanacs, Encyclopedias’, Dictionaries, etc.)
- Odd Index numbers should work on even question numbers. Even Index Numbers should work on odd question numbers.