COMPUTER NETWORK

ABSTRACT

The following portfolio will comprise the INTRODUCTION TO COMPUTER NETWORK (TE121) on my way side it will cover at what extent I learned and enjoyed the course and the archived skills in (TE 121) are helpful in teaching and using ICT in schools, the topic covered are five and ten seminar questions are all in my work that we covered in the second semester of first year. This also was covered in time according to the timetable we had with two hours for normal class and an hour for practical where we did a presentation.

ACKNOWLEDGEMENT

First of all I would like to thank God for his glory and bless up this moment I’m done my task well as planed to be done, honesty I would like to give thanks to the university of Dodoma for providing a nice and suitable environment that helped in taking this course and today results in accomplishing this work.

Sincerely I would like to give more appreciation to my teacher Mr. KOMBA for his contribution during the whole process of learning in order to make sure that we reach the target and to develop the competence teacher.

I would also like to give a lot of appreciation to my fellows who presented their work and others who shared the views about the course also who provided advice about the work accomplishment.

I hope the hope the portfolio will meet the requirements of the university student academicians and common person has the interest in study of ICT, any suggestion or modification to the work script is welcomed

MUTASHOBYA ADRONICUS.

INTRODUCTION

These details contain all things covered in the course of TE 121 in the second semester also many things explained as well as brief explanation but each part thought the lecture, presentations and extra things related to the course. It analyses in this document things explained are network and computer network, transmission media,   network software, application of computer network and the satellites.

MODULE ONE

                                                NETWORK AND COMPUTER NETWORK

A network refers to the connection between two or more devices that enables them to share files, information or signals among users of that network. Computer network is the process of collecting and connecting different computing devices and enable them have the sharing of data or information.

In computer network any device that is being connected is called node and what is being shared among the devices is known as the services.                    

This concept of the computer network may be used or applied in many areas like in business, in education, at home, at military at hospitals and other social issues. In business the computer network may be used though the client server system whereby it involves the request and replies, where one person makes order of the things needed through the network and the other receives the order and makes the replies through the network. Through this people are able to do even business through online purchase and sale, make the view on the currency change in a particular day and time.  For example the value of a dollar compared to the Ural, buying a car online obtaining the book from internet and getting the ticket through a network.

Network is also applied at home where it help much in accessing the remote information, makes people be able to communicate among themselves also in sharing of the information from one colleague to another in the society. This also used in education whereby it computer network help much in finding out the teaching and learning materials in schools and colleges, it also help much in the communication among people in the education sector or among the education stakeholders. The good and well accessible computer network once available help in accessing much of the e-learning where by the student can be able to make the follow up on what is being taught in class while is far away from the area where teaching is taking place also the teacher may be able to access the student while is not in classroom, for example doing of the exam online. Help also in storage of resources that are used in teaching and learning process for the next use and also facilitate in management of the educational program and institution.                          In hospitals it help in disease quire through finding different method of disease medicine and other medication related to the disease, it also assist in doing many scientific research on different kinds of disease that erupt or are virus affected. For example research on HIV/AIDs. People in the society are using networking in finding the information on many matters like politics, employment, marketing, schooling opportunity in the areas.

                                    Advantages of computer network

a.       Sharing of resources among the computers that are connected together. For example sharing the modem, scanner, and printer.

b.      Faster sharing of information and files across the network, this enables most efficient communication among the users of the network.

c.       Helps much in serving the cost since the program may be in one computer and be shared by other computers and all get the access of that program.

d.      The information being stored in the computer network are reliable and up to date and be shared by different people in different location.

Disadvantage of computer network

                   I.            The individuals may fail to obtain the access of the network when the central system is destroyed or fail and this makes both hardware and software non-use.

                II.            Once the whole system is collapse it becomes difficult to trace the problem and make the recover to each computer and once done needs a lot of cost.

             III.            The whole computer network is highly dependent to electric current thus once it is not present the system cannot be archived by the user.

The network can be classified on basing on the geographical area, access restriction and according to the model employed by the node.

In personal area network (PAN); a network sharing of the network is done by few people found in the area of few meters. This method can be conducted either being wired or wireless. In the local area network (LAN); the network sharing is done in the limited geographical area like home, school, hospital, working place and police station. Under LAN one computer may be served as the sever of other computer on which they share a network, where by those computer which shares a network from the central computer are called the working stations. This type is more efficient than the personal network since it accommodates more people in a system used. On metropolitan area network (MAN); is the network that is shared by many individuals in the given geographical area such as city or large companies and this make communication reliable. In the wide area network IS covered under the large area on which many individuals are found. WAN covers a large area such as a country and connects the world together and is more efficient than the all kinds of network although once a system is compromised a problem become difficult to be traced back also once is identified its maintenances becomes more closetful to care it.

The network category can be point to point or a broad cast model. In point to point model the information flows or moves in a specific direction across the network in order to get from one node to the other node. Under this people who communicate are those found in same direction or class whereby under the broadcast model the message sent the message sent or shared by all members in the network. In wireless local area network sharing of the information between the computers is well facilitated among the individuals although this kind involves the use of high cost in doing initial sharing of the information.                                                                       During the initial stage of doing the computer connection involves the use of the devices that help in connection this involves the use of hubs, repeaters, bridges, switch and routers. Those devices when well connected in the manner series they lead to the network topology. Network topology is the way on how different computers and other devices in a network are arranged to each other and the way used by the signals to get transferred from one device to each other device. The route may be bus topology, ring topology and star topology. In bus topology the computer devices are connected in the liner way where the signals are being transferred in a continuation form from one device to the other device. In ring topology the signals being transferred are moving from one point to other point through the cycle form while in star topology the one computer is being connected to other computers which shares the signals from it and this uses the hub to connect the all devices in the network here each device has its own wire which is used to connect it in a central network. This mode has advantage of connecting many devices at a time and once a problem occurs it is easily to trace the problem and get fixed.

Module Two

TRANSMISSION MEDIA  

Transmission media refer to means through which the signals travel over a network. This method of transmission can be guided or unguided media. Conducted media or guided media refer to the one in which there is use of a wire or optical fiber in the transmission of the signals in a network from the sender to the receiver, in unguided or wireless uses the radio waves of different frequencies. Also the transmission media during developing depend on the bandwidth, transmission impairment, interferences and number of receivers. Guided transmission media thus depend on the distance to which signals travels and nature of the media weather is point to point or is multi- point. The twisted pair is highly susceptibility to interferences and noise and once damage occur the repair needs high cost to be used.     

In the unguided or wireless media the signals are being transmitted through all directions and can be received in all directions by many antennas. This kind of connections is much widely used for connecting laptops in the local area network. As many kind are this method is also having its limits such as it is more expensive poor security of data, slow in running the network when many users are present, this is also highly suspected to electrical interference from light and radios.  

The wireless transmission can be infrared transmission in which signals are sent using infrared light waves at a frequency too low of about  (1-4 megabits per second) for human eyes to receive and interpret. Infrared ports are found on laptop computers, wireless mice, printers TV remote -control units and cameras. For communication to take place between the sending and receiving device, the line of sight is required-i.e. there should be no obstacle between transmitter and receive Infrared transmission is confined to short range.

Wireless Fidelity (Wi-Fi). It is a new wireless technology for connecting portable devices and handheld computers to Ethernet LAN. This one it operates 2-25 gigahertz, wireless transmission used up to 300 feet. Allows wide variety of nearby device communicate with one another without physical connection. Bluetooth is a short range digital standard aimed at linking cell phones and is useful for short range communication only. Involves earthbound microwave systems which transmit high-speed radio signals in a line-of-sight path between relay stations spaced approximately 30 miles apart. Use the atmosphere as the medium through which to transmit signals. Cellular phone system is a radio communications technology that divides a geographic area into small areas or cells typically from one to several square miles in area.  This division depends much on the size or the number of users in the given geographical area. Each cell has its own low-power transmitter or radio relay antenna device to relay calls from one cell to another. This technology is used to support mobile phone service, and mobile voice and data communications. This technology is used to support mobile phone service, and mobile voice and data communications.

Digital data/signals are method of storing, processing and transmitting information through the use of distinct electronic or optical pulses that represent the binary digits 0 and 1. Computers and all electronic devices send and receive digital signals.

In analog data/signal wave form (or signal) is characterized by being continuously variable along amplitude and frequency is the number of times a radio wave repeats during specific time intervals. Communication modes, a communication mode specifies the capability of a device to send and receive data it does so by determining the direction of the signal between two connections and this may be simplex mode in which data goes in one direction only or half- duplex mode where the data goes in both directions but at time goes in one direction and in other direction at a next time and when the signals goes in both directions at a time is called full-duplex mode. Also in a computer the devices are not able to communicate to analogue lines and now is able to communicate over the digital signals where by the modem is able to be used and now is translating the analogue signals to digital signals by modulation process and by demodulation where it converts the digital signals to analogue signals which are sent to the network.

Module Three

Application of Computer Network

Web browser application is the application of software designed to enable users of the application to access, retrieve and view document and other resources to the World Wide Web (www). This help much in finding of many useful materials for example Operamin, Google chrome, safari, Firefox.  The primary purpose of the web browser is to bring information resources to the users of the browser in which the access of this depend on the correctly used URL (Uniform Resource Identifier) and the findings may be fining image, video, audio, pages, location and other pieces of content.

Google search engine are program in the browser application which help in searching of the document that are available in the system based on the words of the search terms. For example Google, Bing, and Yahoo although the mostly and commonly used search engine is Google. The searching engine is more efficiently through sing different search methods like use of key words of the search engine, using the correct URL of the certain website which reads to the opening of the relevant pages that are related to the certain search.

The use of Google search method involves the use of different technique search as Boolean And, Boolean Or and those methods helps much in finding of many resources that are more helpful in education and other sectors like business and other social aspects like journey. In education this help in finding of different teaching and learning material like books, stimulations like audio and videos also help in finding dictionary that gives the meaning of difficult words to learners. This search engine helps the parents to obtain the schools for their children and finding their results. In business the search engine also helps the people in business to find the areas where can find the market of goods, finding the stocks, converting of units, flight and searching maps. In the society the search engine may be used in weather forecasting, searching the sun rise and the sun set in different places, finding of the public data, searching movies and other packages. In public data it may be used to search different governmental data such as population, employment. Google hacking is the most method used by the hackers in finding things or webs to be exploited. Hackers are intelligent people with many computer skills and uses those skills to exploit the vulnerability that are present in computer system get compromised. Thus when those vulnerability are not controlled, this lead threats exploitation of the information and the whole system get compromised. The hackers uses different method on the process of hacking through phishing, drive dumping, ring, shoulder surfing , eavesdropping, in this process the attackers of hacking normally follow the procedure before and after hacking they start with reconnaissance, scanning, gaining access, maintain access and covering truck. Although other hackers try to exploit the information and does the disconnection from the internet and then after they reconnect again after installation of new.       

In this networking the page that help the person to view or interact with the page that is intended is called webpage the collection of many pages leads to website. Thus once need to access the certain website one need to know the collect URL which is needed to be used in making the access of the websites.

 Advantages of website

1. Website is more usefully in education, through finding books, journals and simulations.
2. It is used in finding of job opportunities that are found on the area, foreaxample in private organizations and education sector.
3. Finding education stakeholders.
4. It minimizes the cost it is represented as whole.

Disadvantage of website

1. It needs highly level of technology in developing it.
2. Since has built up with many pages, it consumes a time in looking to the specific page.
3. It can be accessed by hacker and study the vulnerabilities present and lead to loss of data.
4. They need to be paid for its presence thus few of organization owns it.

An electronic mail is the established system that is used in communication among people where by the users of a mail is able to send and receive the massage from one individual to the other individual. During communication people can send and receive video, audio, photos, message, documents and other materials. The use of this network needs the internet connection and all users are supposed to have the mail account.

Important things needed during establishing the E-mail

·         The names to be used.

·         Date, month and year of birth. Here the person should be with age of eighteen years and above.

·         Place or the nationality of the individual.

·         Choosing of the strong password. A strong password is the one which cannot be gassed by anyone who use not the user of the mail although it is advised that names of the relatives or hobbies should not be used during creating the password because are the one prone to be hacked.

·         The mobile number to be used in notifications in a mail or during making restore of E-mail account.

Importance of the mail account

v  It enables the user or owner of the account to have a YouTube account.

v  The account helps much in making the blogger of an individual.

v  This help in the installation of the software in androids like watsap.

v  In computer communication it is a safe method which is not prone to viruses.

v  Enables most of people to communicate through this since few conditions are needed.

v  This method is highly prone to be attacked and the communication that is done through this method may be exploited by the hackers.

 

Module four

Network Software

Software is any application that is not manually in the system, in the computer network it involves all application program that are used in network system. In this category there is a protocol which is followed during doing the communication in a network. A protocol is a set of established and agreed system upon the certain need to enhance reliable and effective communication on a network. This protocol can be made by the vendor or by networking standard organization thus involves the set of rules and regulation and procedures for computers to exchange data or information.  For example two computers to exchange data must be in the same protocol and this involves.

Transport Control Protocol (TCP).

Internet Protocol (IP).

Protocol Suite (PS)

 In the Network protocol involves

Internet Message Access Protocol (IMAP)

File Transfer Protocol (FTP)

Hypertext Transfer Protocol (HTTP).

On the above level of communication network protocol one layer on the upper depends much on the lower layer of communication. For example the transfer of one type of the file to be transferred needs the hypertext transfer protocol (HTTP); also the internet message access protocol needs both the hypertext transfer protocol and the file transfer protocol. 

Importance of computer network software                                                                                                                             

v  It helps to send data over the internet.

v  Has an application in e-mail using through communication.

v  Is used in studies like being taught in schools

v  Helps in access of the information when the protocol is well designed

v  The knowledge about the network is used in requesting and delivery of webpage.

Advantages of computer network software

v  Help in communication system among the members of the society

v  Makes people in the areas to send and receive and send the information

v  Helps the students to send their file and other academic work through the e-mail

v  Through used protocol is easily to fix the problem once occurs.

Disadvantages of network software

v  It involves high cost on establishing it

v  Needs the expertise of controlling the whole system

v  The materials needs high cost in managing and maintaining them

v  The system become useless on the remove of the lower layer or network layer and makes the communication to difficult.

v  It has lead to increase of network climes especially for young.

Module FIVE

            SATELLITE

            Satellite communication

Satellites communicate by using radio waves to send signals to the antennas on the Earth. The antennas then capture those signals and process the information coming from those signals.

It is also used for TV broadcasting. Satellites uses microwave frequencies for communication with each other using inter-satellite links and with earth stations.

  Ø   Scientific data (like the pictures the satellite took),

  Ø   The health of the satellite,

  Ø   Where the satellite is currently located in space.

Services offered by satellite services in its types

v  Fixed services satellite (FSS).

Examples Point to Point communication

v  Broadcast services satellite (Direct BS).

Example TVs and Radios

v  Mobile service satellite.

Example satellite phones

Types of satellite

i) Satellite orbit

A. Geostationary Earth Orbit (GEO)

B. Low Earth orbital (LEO)

C. Medium Earth Orbit (MEO)

D. Molniya

E. HAPs

ii) Frequency band

a) L-band 1 to 2 GHZ Used by Mass

b) S-band 1 to 4 GHZ Used by Mass and NASSA

c) C-band 4 to 8 GHZ Used by FSS

d) X-band 8 to 12.5 GHZ Used by FSS

e) KU-band 12 to 18 GHZ Used by FSS, BSS(DBS)

f) K-band 18 to 26.5 GHZ to FSS, BSS(DBS)

g) Ka-band 26 to 40 GHZ to FSS

Advantages of Satellite Communication

·         It is used for mobile and wireless communication applications independent of location.

·         It covers wide area of the earth hence entire country or region can be covered with just one satellite.

·         It co-exists with terrestrial microwave line of sight communication.

·         It is easy to install and manage the ground station sites.

·         It does not incur much of the costs per VSAT site.

·         It has small fading margin on the order of about 3dB.

·         It is used in wide variety of applications which include weather forecasting, radio/TV signal broadcasting, gathering intelligence in military, navigation of ships and aircrafts, global mobile communication, connecting remote areas

·         LEO and MEO satellite types have lower propagation delay and lower losses compare to GEO satellite. This will help them to be used for global coverage.

Disadvantages of Satellite Communication

• Satellite has been constructed for years. Moreover satellite design and development requires higher cost.
• Satellite once launched, requires to be monitored and controlled on regular periods so that it remains in the orbit.
• Satellite has life which is about 12-15 years. Due to this fact, another launch needs to be planned before it becomes un-operational.
• Redundant components are used in the network design. This needs more cost in the installation.
• In the case of LEO/MEO, large number of satellites is needed to cover radius of earth. Moreover.

Part two

Further readings on Computer Networking

Introduction

A collection of two or more computers interconnected by the telephone lines, co-axial cable, satellite links, radio and microwave transmission and some other communication techniques.  A computer network is a group of computers that are connected together and that communicate with one another for a common purpose.

Although the computer industry is young compared to anther industries (e.g., automobiles air transportation), computer have made spectacular progress in a short time.  During the first two decades of their extrinsic, computer system highly centralized, usually a single large room.  A medium size company or university might have had one or two computers, while large instructions had at most a few dozen. The idea that within 20 years equally powerful computers smaller than postage stamps would be mass produced by the millions was pure science fiction.

The merging of computers & communications has had a profound influence on the way computer systems are organized. The concept of the computer center as a room with a large computer to which users bring their work for processing is now totally obsolete. The old model of single computer serving all of the organizations computational needs has been replaced by one in which a large number of separate but interconnected computers do the job. These systems are called computer networks.

Two computers are said to be interconnected if they are able to exchange information’s. The connection need not be via a copper wire; fiber optics, microwaves, and communication satellites can also be used. By requiring the computer to be autonomous, we which to execute from our definitions systems in which there is a clear master/slave relation. If one computer can forcibly starts , stop, or control another one, the computers are not autonomous. A system with one control unit and many slaves is not a network; nor is a large computer with remote printers and terminals.

There is considerable confusion in the literature between a computer network and a distributed system. The key distinction is that in a distributed system, the extended of multiple autonomous computers is transparent to the user. He can type a command to run a program. And it runs. It is up to the operating system to select the best processor, find and transport all the input files to the processor, and put the result in the appropriate place. In other words, the user of a distributed system is not aware that there are multiple processors; it looks like a virtual uni-processer. A location of jobs to processors and files to disks, moment of files between where they are stored and where they are needed, and all other system functions must be automatic.

With a network, user must explicitly log on to one machine, explicitly submit jobs remotely, explicitly move files around and generally handle all the network management personally. With the distributed system, nothing has to be done explicitly it is all automatically done by the system without the users knowledge.

In effect, a distributed system is a software system built on top of a network. The software gives it a high degree of cohesiveness and transparency. Those distinction between a network and a distributed system lies with the software rather than with the hardware. Nevertheless, there is considerable our lap between the two subjects. E.g., both distributed system and computers networks need to move file around. The difference lays in whom in vokes the movement, the system or the user.

Local Area Networks (LAN):

Local area network, generally called LANs, is privately-owned networks within a single building or campus of up to a few KM in size. They are widely used to connect personal computers and workstation in company offices and factories to share resources (e.g., printers) and exchange information. LANs are distinguished from other kinds of networks by three characteristics:

1.      Their size,

2.      Their transmission technology,

3.      Their topology.

LANs are restricted in size, which means that the worst-case transmission time is bounded and known in advance. Knowing this bound makes it possible to use certain kinds of designs that would not otherwise be possible. It also simplifies network management.

Metropolitan Area Networks (MAN):

A metropolitan area network, or MAN (plural: MANs, not MEN) is basically a bigger version of a LAN and normally uses similar technology. It might cover a group of nearby corporate offices or a city and might be either private or public. A MAN can support both data and voice, and might even be related to the local cable television network. A MAN just has one or two cables and does not contain switching elements, which shunt packets over one of several potential output lines.

Wide Area Networks (WAN):

A wide area network, or WAN, spans a large geographical area, often a country or continent. It contains of machines intended for running user (i.e., application) programs. We will follow traditional usage and call these machines hosts. The term end system is sometimes also used in the literature. The hosts are connected by a communication subnet, or just subnet for short. The job of the subnet is to carry messages from host to host, just as the telephone system carries words from speaker to listener. By separating the pure communication aspects of the network (the subnet) from the application aspects (the hosts), the complete network design is greatly simplified.

In most wide area networks, the subnet consists of two distinct components: transmission lines & switching elements. Transmission lines (also called circuits, channels, or trunks) move bits between machines.

The switching elements are specialized computers used to connect two or more transmission lines. When data arrive on an incoming line, the switching element must choose an outgoing line to forward them on.

In most WANs, the network contains numerous cables or telephone lines, each one connecting a pair of routers. If two routers that do not share a cable nevertheless wish to communicate, they must do this indirectly, via other routers.  When a packet is send from one router to another via one or more intermediate routers, the packet is received at each intermediate router in its entirety, stored there until the required output line is free, and the forwarded.  A subnet using this principle is called a Point to Point, store and forward or packet switched subnet.  Nearly all wide area networks (except those using satellite) have store and forward subnet.  When the packet are small and all the same size, they often called cells.

Wireless network:

Mobile computers, such as notebook computers and personal digital assistants (PDA) are the fastest growing segment of the computer industries.  Many of the owners of these computers have desktop machines on LAN’s and WAN’s back at the office and want to be connected to their home base even when away from home or en route.  Since having a wired connection is impossible in cars and airplanes, there is a lot of interest in wireless network.

Wireless networks come in many forms. Some universities are already installing antennas all over campus to allow students to sit under the trees and consult the libraries card catalogs.  Here the computers communicate directly with the wireless LAN in a digital form.  Another possibility is using a cellular (i.e. portable) telephone with a traditional analog modem.  Direct digital cellular service, called CDPD (Cellular Digital Packet Data) is becoming available in many cities.

Network Hardware

It is now time to turn our attention from the application and social aspects of networking to the technical issues involved in network design. There is no generally excepted taxonomy into which all computer network fit, but two dimensions stand out as important: transmission technologies and scale. We will now examine each of these in turns.

Broadly speaking, there are two types of transmission technologies:

1. Broadcast networks.
2. Point-to-point networks.

Broadcast networks: It have a single communication channel that is shared by all the machines on the network. Short messages, called packets in certain contexts, sent by any machine are received by all the others. An address field within the packet specifies for whom it’s intended. Upon receiving a packet, a machine checks the address field. If the packet is intended for itself, it process the packet, if the packet is intended for the other machine, it is just ignored.

Broadcast systems generally also allow the possibility of addressing a packet to all destinations by using a special code in the address field. When a packet with this code is transmitted, it is received and processed by every machine on the network. This mode of operation is called broadcasting. Some broadcast system also support transmission to a subset of a machines, something now has multicasting.

Point-to-point networks: It consists of many connections between individual pairs of machines. To go from the source to the destination, a packet on this type of network may have to first visit one or more intermediate machines. Often multiple routes, of different lengths are possible, so routing algorithm play an important role in point-to-point networks. As a general rule (although there are many exceptions), smaller, geographically localized networks tend to use broadcasting, where larger usually are point-to-point.

Whenever we want two devices – transmitting and receiving device to communicate with each other, we need hardware’s to achieve that.  We would be discussing about the various hardware such as:

1.      Sender and Receiver hardware

2.      Communication devices

3.      Communication channels

  Sender and Receiver Hardware:

Following hardware are used for handling communication messages, data transfer etc.

Nodes and workstations:

Data communication is done using various communication devices and softwares interconnected for information exchange.  The devices used to communicate a data in communication network are called Workstations.  These workstations may be computer, terminal, printer, telephones and other communication devices.  Each workstation is connected to something called a Data Communication Network Mode.

Multiplexer: As the name suggests, multiplexing is a form of data transferring which are communication channels and is used for several transmission.  For e.g. the telephone lines that we used for our daily conversation can carry 100’s and even 1000’s of conversations using multiplexing.  In other words multiplexing is a type of network which allows a number of simple, low cost terminals to share each communication lines introduces almost no delay and requires no special computer software.

Communication devices: There are several types of communication devices or interface used in data communication.  These interfaces are connection between receiver and sender hardware involved in data communication and the communication network.  Some of these interface or communication devices are discussed below:

1.        Modems: Modulator and Demodulators are devices which converts digital signals in to analog for transmission over the analog transmission facilities such as telephones.  At the receiving end, a modem performs the reverse function and converts analog signals into digital form.

2.        Codec performs the opposite function of a modem.  A communication port / adapter is a connector on the computer, which is used as an entry to departure point for data involved in data communication.  A common type of communication port is RS-232c.  This adapter is used for transfer of data between the computer and the telephone lines.

3.        Line Drivers are simple devices used to transmit digital signals over short distances.  These devices do not modulate or demodulate signals, but use filters to reduce the high frequency components and the modified signal is transmitted directly over the media. 

Communication channels:

The most basic hardware required for communication is the media through which data is transferred.  There are several types of media, and the choice of the right media depends on many factors such as cost of transmission media, efficiency of data transmission and the transfer rate.

Some of the following transmission Medias is as follows:

1. Two wire open line:  This is the simplest of all the transmission media.  It consists of a simple pair of metallic wires made of copper or some times aluminums of between 0.4 and 1mm diameter, and each wire is insulated from the other.   There are variations to this simplest form with several pairs of wire enclosed in a single protected cable called a multi core cable or molded in the form of a flat ribbon.

This type of media is used for communication within a short distance, up to about 50 M, and can achieve a transfer rate of up to 19200 bits per second.

a.       Twisted Pair cable: A twisted pair consists of a pair of insulated conductors that are twisted together.  The advantages of a Twisted Pair cable over the Two Wire Open Lines are; it provides better immunity from spurious noise signals.  As the Two Wires are closed to each other, both pick equal interferences caused by extraneous signal sources and this reduces the differential signal added by the noise. Twisted Pair cable is used for communication up a distance of 1 KM and can achieve a transfer rate of up to 1-2 MBPS.  But as the speed increased the maximum transmission distances reduced, and may require repeaters.

 

Twisted pair cables are widely used in telephone network and are increasingly being used for data transmission.

v  Co-axial Cable: A co-axial cable consists of a solid conductor running co-axial inside a solid or braided our annular conductor.  The space between the two conductors is filled with a dielectric insulating material.  Larger the cable diameter, lower is the transmission loss, and higher transfer speeds can be achieved.  A co-axial cable can be used over a distance of about 1 KM and can achieve a transfer rate of up to 100 MBPS.

 

A co-axial cable is of two types- a 75 Ohm cable which is used by the cable TV operators and 50 Ohm cable which is used in high speed broad band networks and is low loss cables.

Fiber Optic Cables:

 

A fiber optic cable carries signals in the form of fluctuating light in a glass or plastic cable. An optical fiber cable consists of a glass or plastic core surrounded by a cladding of a similar material but with a lower refractive index. The core transmits the light while the change in refractive index. The core transmit the light while the change in refractive index  between the core and the cladding causes total internal reflection, thus minimizing the loss of light  from fiber.

As light waves gave a much wider wand width then the electrical then the electrical signal and are immune from electromagnetic interferences, this leads to high data transfer rate of about 1000 mega bites per second & can be used for long & medium distance transmission links.

Radio, Microwaves & Satellite Channels 

Radio, Microwaves & Satellite Channels use electromagnetic propagation in open space. The advantage of these channels lie in their capability to cove large geographical areas & being inexpensive than the wired installation.

The demarcation between radio, Microwave & satellite channels lie in the frequencies in which they operate. Frequency bellow 1000 MHZ are radio frequencies & higher the Microwave frequencies.

The radio frequency transmission may be bellowing 30 MHZ above 30 MHZ & thus the techniques of transmission are different. Owing to the characteristics of the ionosphere, frequencies bellow 30MHZ are reflected back towards the surface of the earth. Above 30Mhz propagation is on line of sight paths. Antennas are placed in between the line-of- sight paths to increase the distance. Radio frequencies are prone to attenuation and, thus, they require repeats along the path to enhance the signal. Radio frequencies can achieve data transfer rate of 100 Kbps to 400 Kbps.

Microwave links use line- of- sight transmission with repeaters placed every 100-200 Kms. Microwave links can achieve data transfer rates of about 1000 Mbps.

Satellite links use microwave frequencies is the order of 4-12 GHz with the satellite as a repeater. They can achieve data transfer rates of about 1000 Mbps.

Network Concept and Classifications:

Communication using computer has brought a revolution in the world of computer technology, particular in the field of computers.  We have always heard of networking or the term network, a network is a way or means of transmitting or receiving information one or more sources.  As an e.g. car salesman after years in the business, have developed a network of associates. When the car salesman needs a car to make a sale the car salesman calls out to his network to retrieve information on the location of the car. Employment agents also develop a network. Their customers become their network. Employment agents will frequently keep in touch with their clientele for possible openings or to locate a candidate for an opening. Without the capability of networking, these two people would have a difficult time. It is the same in computing. Networks provide the means for locating transporting information.

 In computing networks, the origin of the information request utilized the service of a network to locate & return the information. This is done with addresses. In the two previous examples of the car sales man & the employment agent, a telephone number can be considered the address of their associate or client. Addresses in computer networking are used in the same manner. These addresses identify the network resource. There are two popular architectures for networking – hierarchical & peer.

Hierarchical addressing is defined in a master slave relationship. In hierarchical network, the master controls the network & therefore assigns addresses to the network resource. This architecture has the mainframe as the master & all network resources as slave. The bases of this is that if the master does not know beforehand of a network resource existence through a pre- defined address then that resource cannot participate in the network.

Peer networking does not need pre- defined networking addressing. Instead, each resource on the network is seen as a peer. Each network resource is a peer to the other network resource. When a new network resource joins the network it introduced itself & notifies its peer to any other network resources that it knows about peer networks are share network information. The entire computer network can be classified into two board categories. They are (a) LAN (Local Area Network) (b) WAN (Wide Area Network)  

LAN (Local Area Network)

As numbers of system grow within an organization, a need is felt for sharing expensive resource and exchanging data and information between systems. This need of information exchange and resource and sharing with in a organization has given birth to a local area network or LAN.

A LAN is a data communication network, which connects many computers or workstation (Computer’s Terminals, Printer etc.) and permits exchange of data & information among themselves, with in a localized area, typically confined to a building, or a cluster of buildings. The distance between two communications prints connected on the same LAN channels is usually up to 02 to 05 kms.

LANs are not rigidly defined but tend to share most of all of the following characteristics.

§  The transmission media is shared by all the connected devices in the network.

§  Each device is connected in the network can either operate stand alone or in the network.

§  Area covered is small.

§  Data transfer rates are high, usually 1 Mbps- 100 Mbps (Million of bits per second).

§  Each device connected in the network can communicate with any other device in network.

§  Cost of setting up the network is usually low.

LAN Topology

A network topology refers to the physical lay out of the network in which all the devices are connected. This includes all the hardware that makes up the network. The points of the connection to the network by the station are calls Nodes or Link stations. There are several types of topographical design & strategies are used to implement LAN. The majority of these are based on three types of topologies.

            a) Star             b) Bus             c) Ring

Each topology has its advantages & disadvantages.

Star Topology

Star topology is shown bellow. In this topology. A number of stations are connected directly to a central station or controller. Communication on the connecting links between the stations & the central station of the star topology can be bi- directional and are point to point. A station on this type of network passes an information frame to the central controller, which then forwards the information to the destination station. The central controller manage and controls all communication between stations on the network.

 

                                                                                   

Star Network

Failure of a station on a star network is easy to detect and can be remove from the network. However, failure of the central controller will disable communication through out the whole network.

Bus Topology

 A bus topology is shown bellow all stations are connected to a single communication line. This single communication line is referred to a bus. Information frames originating at a station are propagated away from the station in both directions on the bus. Each station on the bus interrogates the information frame destination address failed for its on addresses. If the destination failed does not mach the station address, the station discards the information frame back on to the bus. If the destination address matches the station addresses, it accepts the information frame & processes the frame.

An extension to the bus topology is tree topology is in the following figure. Tree topology extends the branches of the bus topology allowing more stations to access the bus.

	NODE			NODE		NODE		NODE

 

Bus Topology

On a bus or tree network there is no central point for management & control.  These function ions are distributed to each station on the bus. A brake in the bus can be difficult to locate but limits the outage to communications between stations that traverse the broken point.

Ring Topology

A ring topology is shown bellow. Local area network that have each station attached to an adjacent station using point to point links from a physical ring. Each station attached and active to the ring regenerate the information frame, then retransmits the information frame on the ring. The ring itself is logically circle and the information travels in one direction.

		Ring Topology

 

Failure of a station in a ring topology disrupts the ring because the information frame is not regenerated. Additions or deletions of stations of the ring can be disruptive, if the changes are not managed properly.

LAN Hardware and Software

As we have seen so far, to realize a LAN process, several functions are to be performed. These are so specialized in nature the require hardware specially built for such purpose. Here we will discuss briefly the basic hardware components of LAN, these are:

(A)  Network Interface Unit (NIU)

(B)   Servers

(C)   Work Station

A)    Transfer mission Channels

Generally following four types of channels are used for data communication in a LAN. They are:

(i) Twisted Pair Cable

(ii) Coaxial Cable

(iii) Fiber Optic Cable

(iv) Radio waves

B)    Network Interface Units (NIU)

Network interface units connect each device in the LAN network to shared transmission device. It contains the rules or logic to access the LAN. NIU is also used for to implement LAN protocols and for device attachments. Its functions depend on the type of topology used in LAN.

C)     Servers

One of the major benefits of implementation of LAN is sharing expensive resources such as storage device, printer etc. this is achieved through providing servers on the LAN. It is a dedicated computer that controls on or more resources. This contains both hardware & software for LAN. Three major categories of servers used in LANs are

(i)                 File Server

(ii)               Printer Server

(iii)             Modem Server

In a networking file server is used to share storage space for files. Beside providing storage space for files in a LAN environment, it is used for talking periodical backup, and also to provide gateway to other servers with in & between LANs.

Similarly printer server is use to handle printing works of all workstations connected in the network. In the LAN environment also modem is required to get connected to other network or simply to use a telephone. A modem server is used to share these expensive resources by all connected workstation in a networking ring.

LAN Software/ Operating System

As the name suggest LAN operating system is required to operate on the LAN system, manage the tremendous work load with a number of various types of server attached to it. It has basically two aspects (i) Server Software (ii) Work station Software. As case of other multi user operating system, LAN operating system also facilitate the sharing of expensive resources such as printer, storage space etc. among all LAN users, provides security of data permits connections to other network.

There are various types of LAN operating systems for example Novel Netware, LAN server, omni met, PC Net, IBM PC LAN, Etherlik plus etc.

 WIDE Area Network

As the name suggest, WAN spread across countries and continents satellites being one of the transmission media.

A wide area network WAN is a network that links separate geographical location. A WAN can be a public system such as the Public Switched Telephone Network (PSTN) or one of the various packet switched services provided by the public telecommunication authorities. WANs can also use most other types of other types of circuit including satellite networks, ISDN, Value Added Networks (VANs/VADs). The network can be a private system made up from the local telephone company or set up using public systems as virtual private network. A virtual private network is one which operates in the same way as a private network but which uses public switched services for the transmission of information.

The main distinguishing feature between a LAN and WAN is that, the LAN is under the complete control of the owner, whereas the WAN needs the involvement of another authority like the telephone company. LANs are also able to handle very high data transfer rates at low cost because of the limited area covered. LANs have a lower error rate then WANs.

Communication Switching Techniques

In a WAN, two computing devices are not connected directly. A network of switching nodes provides a transfer path between the two devices. The process of transferring data blocks from one node to another is called data switching.

There are three switching techniques commonly employed and these are:

i)                    Circuit Switching

In circuit switching there is a dedicated communication path between the sending and receiving devices. The dedicated path is a connected sequence of links switching nodes. A conventional telephone network, where a dedicated path is set between the called parties for the duration of a telephone call is an example of circuit switching.

Communication viz. circuit switching involves three steps-circuit establishment; data transfer; and circuit termination. Circuit switching is mainly used for voice telephone network, but is not that effective for data communication network, as channel capacities are not fully utilized, as data communication equipments do not generate data continuously.

ii)                  Massage Switching

Massage switching is an alternative switching techni8que, where it is not necessary to establish a dedicated path between the sending and receiving devices. In massage switching, the sending device appends the destination address to the massage and passes to the network; the massage is then passed through the network from one node to another till it reaches the intended destination. Each switching are electronic mails, computer files, telegrams and transaction queries and responses. A complete exchange may consist of several messages.

The basic disadvantage of massage switching is the variable delay at intermediate switching nodes.

iii)                Packet Switching

Packet switching combines the advantages of message & circuiting switching. Packet switching is functionally similar to message switching, in which data is transmitted in blocks, stored by the first switching node it meets in the network and it forwarded to the next and subsequent downstream nodes until it reaches the destination. The length of data block is limited in packet switching network. Typical maximum length of packets is between 128 bytes to 4096 bytes. There are two approaches to packet switching:

In datagram approach, each packet is treated independently and may follow a different path through the network. Packets may be reordered, dropped or delivered in wrong sequence. The communication protocols provide the error recovery sequencing of packets at the receiving device.

In virtual circuit approach, a fixed logical path through the network from the sender to the receiver is established before any packets are sent. This path remains unchanged for the duration of the session. This is quite like circuit switching, but no resources are reserved along the path. Packets are buffered at intermediate nodes awaiting transmission.

WAN Devices / Hardware

The switching techniques utilized the routine technology of data transfer. Routing is responsible for searching a path between two computing devices that wish to communicate and for following the data packets on this path. Devices such as bridges, router and gateway provide this routing function.

i)                    Bridges

Bridges are used to connect two LANs that use identical LAN protocols over a wide area. The bridge acts as an address filter which picks up packets from one LAN that are identical for a destination on the another LAN and passes these packets on the network. Bridges operate at the data link layer (layer 2) of the OSI model. As all devices use the same protocols, the amount of processing required at the bridge is minimal. If the distance between the two LANs is large, the user would require two additional bridges at either end of the communication link.

ii)                  Routers

Routers can be used to connect networks that may not be similar. Routers provide connectivity between two LANs or two WANs over large geographical distance. Routers operate at the network layer (layer 3) of the OSI model. All routers participate in routing protocols to access the network topology, and based on this information routers computes the best route from a sender to the receiver,

For large wide area network spanning thousands of kilometers, the normal practice is to put network routers at suitable locations to minimize link cost for leased link and provide adequate reliability from link failures. Networks and other system are then connected to the nearest router.

iii)                Gateways

Gateways are used to connect to dissimilar LANs. The term gateway and routers are used interchangeably, though there is a subtle difference between the two. A router operates at the network layer (layer 3) of the OSI model, whereas a gateway operates on the application layer (layer 7) of the OSI model. A gateway is required to convert data packets from one protocol format to another before forwarding it, as it connects two dissimilar networks.

1. Public Networks

Public networks are those networks which are installed and run by the telecommunication authorities and are made available to any organization or individual who subscribe. Examples include Public Switched Telephone Networks (PSTN), Public Switched Data Network (PSDN), Value Added Service (VANs/ VADs) and the Integrated Service Digital Networks (ISDN). We would be discussing the main features of there services:

a)      Public Switched Telephone Network (PSTN)

The features of the PSTN are its low speed, the analog nature of transmission, restricted bandwidth & its wide spread availability. As PSTN is designate for telephones, modems are required when it is used for data communication.

b)     Public Switched Data Network (PSDN)

The term PSDN covers a number of technologies; all through currently it is limited to Public Packet Switch Networks available to the public. The main features of all PSDNs are their high label reliability and the high quality of the connection provided. The can support both high & low speeds at appropriate costs.

c)      Value Added Services (VANs/ VADs)

In value added services, the provider of such services must process, store and manipulate the data that is carried on the network, that add value to it. The technique can be used in specific types of business in which it is advantageous to be able to share information with other companies in the same line.

d)     Integrated Services Digital Network (ISDN)

 The ISDN is the networking concept providing for the integration of voice, video and data servicing using data service using digital transmission combining both circuits and packet switching techniques. The motivating force behind ISDN is that telephone networks around the world have been making a transition towards utilizing digital transmission facilities for many years.

b)     Private Networks

The basic technique used in all forms of private WAN is to use private (or more usually leased) circuits to link the locations to be served by the network. Between these fixed points the owner of the network has complete freedom to use the circuits in any way they want. They can use the circuit to carry large quantities of data or for high speed transmission.

Private WIDE area network can be built using whatever standard technology is available. The way private networks have generally been set up has to specify .

 

  

Part Three

PRESENTATIONS

QUESTION 01

By using a modem in a laptop computer, explain practically how you can create a network account and share to other computers supporting Wireless Network.

M

odem is device or program that convert digital computer signal to analog signal to transmit data over telephone or cable line then to receive these signal and convert back to digital signal.

Computer information store digitally telephone transmitted over the telephone transmitted in the form of analogy. The modem sending modem modulates the data into a signal with phones line, and receiving modem demodulates the signal back into digital data.

Wireless modem convert digital data into radio signal and back. There part of connection modem of the main computer which receive the network for modem.

The steps that used before create new account

v  Insert subscriber identity module (SIM) into the modem.

v  Insert the modem into the computer through the universal serial bus port (USB).

NOTE: If modem is used for first time in the computer install the modem software.

The following are the steps creation a network a new account as follows by using modem.

✓ click the start bar.

✓ click the control panel.

✓ Click network and internet.

✓ Click network sharing and sharing center.

✓Then choose and click set up a new connection and network.

✓ Click set up wireless ad hoc (computer to computer) network.

✓Then create account by naming network account and security key.

 The security must contain 8-63 characters.

➢Then save and click next for to allow internet connection sharing.

Then save and click next for to allow internet connection sharing.

Alternatively way.

➢ Click network icon.

➢ Click open network and network Centre.

➢Then choose and click set up a new connection and network.

➢ Click set up wireless ad hoc (computer to computer) network.

➢Then create account by naming network account and security key.

➢Then save and click next for to allow internet connection sharing.

The follows are step of sharing the network to other computer.

➢ Click the start bar.

➢ Click control panel.

➢ Click network and internet.

➢ Click connect to network.

➢Choose the account name from host computer and connect.

➢Then write password from host computers

➢Now the computer is able to share the network with other computers.

QUESTION 02

What is blog? Practically explain how to create a simple blog (you can create a class blog) show a class how the blog owner will sign in the blog and add the information to it ? How others users can access your blog? What they can do and cannot do to your blog?

B

log can be defined as the place of express yourself to the world. OR It is a place to share your thoughts and your passions. Blogger is a person who keeps a blog. Also sometime can be a tool for creating a blog like Google blogger. Blogging is an action of writing a blog and adding information.

For examples of common blogs in Tanzania are Maswayetu blog, Muungwana blog, millardayoblog, Mzalendo blog, Jamifolum blog, Mpekuzi blog, Massage blog. Requirements for creating blog E-mail account which could be used in signing up and in, this can be from gmail, yahoo and others.

 The needed procedures of creating a blog are

v  The first thing to do is to open the search engine such as a Google and then type the word ‘blogger’ then you click search

v  After obtaining the result then you select the option written “create a unique and beautiful blog. it's easy and free.”

v  After selecting an option of creating a unique and beautiful blog you will find an option written “create a blog” then select it.

v  When you select that option u will have to enter the gmail account then click next where you will enter the password of the gmail account.

v  Enter the recovery Email account and click next.

v  Till here you will have already a blog but you will not be able to post anything until you open the smallest blog within the largest one.

v  This will have option where you can enter the title of and the address of the blog then you will click continue then you will see Congratulation,, “Your blog has been created” on the screen then click  “start blogging now”.

The owner of a blog can post information in the blog through:

 Typing in the words needed to be posted and then after have to publish the post. Posting stored document by following the steps like:

1) Click the new post button at the top.

2) Type the post title on the post title bar at the top.

3) Insert an image relating to your post.

4) Go to your stored document, copy and paste it on the texting field of the posting place on your blog.

5) Go the post settings, click on labels button to categorize your post.

6) Then click done and publish it.

How other user of the blog will access your blog, the other user will be able to access into the blog by typing the blog address on any browser. Example adronicus.bogspot.com

How the owner of the blog can sign in and sign out. To sign in the blog

A.By searching the word blogger through your search engine and the typing in the e-mail address of the blog owner.

steps to fallow

i.          Type the word blogger and search for it through a search engine .

ii.         Then select an option of creating simple and beautiful blog and click to search for it

iii.        Two options will appear after the search is complete, create a blog and sign in then click on sign in option.

iv.        Then enter your Gmail account, click next and enter your password and click next.

B.        Sign in using your Gmail account

Steps to fallow

i.          Sign in into your email

ii.         Click on google apps option at the top right.

iii.        Select more options and click on blogger applications.

TO SIGN OUT

  To sign out the owner can press or click the icon of email on the right Conner and select sign out. After then the owner will be already signed out of the blog.

WHAT PEOPLE CAN DO AND CAN NOT DO IN MY BLOG!

         People can add comments on a blog and you can restrict adding comment on blog.

         You can set a blog to be viewed by public, private.

         You can add author to your blog that will have the same authority with. He/she can add any information, edit, and post anything.

QUESTION 03

Searching information in a network is a skillful task that requires the searcher to have considerable techniques on searching information in a network. Basing on this clue, explain practically different search engine techniques

S

earch engine is the software system that is designed to search for information on worldwide web. (www). Example of search engine Google, Bing, Yahoo, Ask.com, Aol.com, Baidu, Internet archive, Chacha.com, search. The following are techniques of search information in network search engine.

Google scholar: This is the techniques which provide the simple broad search of scholarly literature, by using Google scholar one may search different material across many disciplinary such as books, articles and different scholar research from different academic publishers. Google scholar ranks the document from the way researcher do, means the full text for each document, where it was published, who has written it and how it was cited from other scholar research. In the Google search one have to type Google scholar and Google scholar search box will appear where one can type to search.

Google books: This is the technique used to search the full text of books that Google has scanned and store on it database. It allows users to view pages from book which appear in the search terms. Books can searched by typing the name of the book or the name of the author, also the genre of the book thus in Google search one have to type Google books and the Google book search box will appear here one can write the name of the book or author. In Google book, books which are public are available for full view and can be downloaded for free. Also there are books which can be full viewed only if the publisher has given permission. And there are preview books which are restricted to a limit number of pages to be viewed by users.

Google calculator: Google calculator' this technique enable us to perform different calculations through Google search engine. Calculations like addition, subtractions, multiplication and other mathematical problems can be solved by Google search engine. On how to use this technique go to Google then type you calculation 

Google map: A Google map is a web mapping service developed by Google. It offers satellite imagery, street map 360˚ panoramic views of street, real-time traffic condition and route planning for travelling by foot, car, bicycle or public transportation. The following are the procedure of Google mapping. First step go Google then write “Google map”, after that you may get many option, then click Google map.

Google  phet simulation: The suite of research based interactive computer simulation for teaching and learning physics, chemistry, math and other science subject. This can run online or downloaded free from the website. Google phet simulation is using of searching engine to search the different simulation.

QUESTION 04

What is Google hacking? Practically describe different Google hacking techniques

G

oogle hacking, also named Google docking, Google hacking is the use of a search engine, such as Google, to locate a security vulnerability on the Internet. Google hacking involves using advanced operators in the Google search engine to locate specific strings of text within search results.

Search within a specific site or domain site:

       Ø   Use the site: operator to search for information within a specific website or type of site (.org, .edu). [ site:linkedin.com ] or [ site:edu ] Also search within specific sub-domains. [ site:www.linkedin.com or site:plus.google.com ]

Search for a specific term within the Title of a website intitle:

       Ø   Place intitle: immediately in front of your query to search for a specific term or phrase within the Title of a website or page. [ intitle:resume ] or [ intitle:“resume software engineer” ] Tip: Use quotes when searching for specific phrases.

Search by file type filetype:   

       Ø   Use the filetype: operator to search for specific types of files, such as PDFs, DOCs, or XLS [ filetype:pdf ] Tip: Because file type searches are generally obscure by nature, it’s best practice to include multiple extensions. Example: (filetype:doc | filetype:pdf | filetype:rtf | filetype:txt).

Search for terms within the URL of a website inurl:

       Ø   Search for a specific term or terms within the URL of a website. [ inurl:resume ] Tip: The query must be a complete or whole term, meaning that you cannot extract a term from a string of consecutive letters or numbers. Using the above example, the following demonstrates what is and is not possible when using the inurl: operator. Yes: [ my-resume-123 ] or [ my/resume/123 ] No: [ myresume123 ]

Google’s hacking techniques

1.         GOOLGLE MENTALPLEX: You have to use these technique of Google hacking to hack various page in Google, to do this you have type the word Google mentalplex in Google you will find the page if actually from a Google .. It was posted for April 2000 fool’s day.

If you click on it, it sends to another page with a lot of information making fan of you where you can choose and see its details. For example you can open the page which acquire to choose among of difference pages motioned or if your page which acquire you not mentioned above then you can turn back and type that kind of page which acquire you then place on it, then the page will open and start to peruse that kind of information on that page. for example you need the page of ‘Tasisiya Kiswahili Tanzania’, then will type these page above on given place to type then click on it then the page will be open then several information will happen then select what you want to see.

2. GOOGLE GRAVITY:  These is another technique in Google hacking which you may use to hack different information and other techniques like how to play Quitter, Terminals and snake games and other techniques which acquire you. Therefore if you want to use these technique to hack information in Google you have to type ‘Google gravity’ on Google then you will find a threat part web page calwel Google and you will see the simulating Google part of moving of phenomena these can be impressive for few second if you step away from you computer is well and see the reaction of someone who does not know this trick on the same note you can find on this web site few more tricks like play Quitter, snake game and packman.

3. MATH TOOL FORMULAS: If you type math formulas in Google then you will get more information about mathematic calculation/ problems and you can perform different calculation as well as drawing graphs using Google

4. ATARI BREAKOUT: These are few magic words that provide a search result with a games that you can play during working hours in order to refresh your mind. The trick is to click on the image result rather than word result then you can have some fun when playing this game.

5. GOOGLE DOODLES: If you do not search anything but still press the I’m feeling lucky button you will get all the Google’s doodles that Google has used in the past for specific event and for specific country. You need to understand that Google has different depend on the way you’re with different logos.

            QUESTION 05

With examples, differentiate between website and WebPages. Explain practically how we can get different educational resources from different websites.

            QUESTION 06

Practically describe how to create different email accounts. Mention other accounts that comes with Gmail account and explain how to use these accounts

SOLUTION:

            QUESTION 07

What is Carbon Copy (CC), Blind Carbon Copy (BCC), Sign in and Sign up as applied in emails? Using Gmail account explain practically how to attach different types of files while sending emails. What the maximum data size that can be attached and sent using Gmail?

S

IGN IN. This referred to the process of logging into the E-mail account. And SIGN UP means opening new account in E-mail. They are done when a person needs to access an email account and also need to create a new account.

Electronic mail, or email, is a method of exchanging digital messages between people using digital devices such as computers, mobile phones and other electronics. Email operates across computer networks, which today is primarily the internet. Some early email systems required the author and the recipient to both be online at the same time, in common with massaging. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously. Internet email messages consist of two major sections, the message header and the message body, collectively known as content. The header is structured into fields such as To, CC, BCC, Subject, Date, and other information about the email. The body contains the message, as unstructured text, sometimes containing a signature block at the end. The header is separated from the body by a blank line.

Common header fields for email include;

 TO…

 CC…

 BCC…

 SUBJECT…

To: The email addresses (es), and optionally name(s) of the message's recipient(s). Indicates primary recipients (multiple allowed), Cc stands for "carbon copy." Anyone you add to the cc: field of a message receives a copy of that message when you send it. All other recipients of that message can see that person you designated as a cc: recipient. To add an entry in the cc: field, click the Add cc: link under the To: field. Bcc: stands for "blind carbon copy." Anyone you add to the bcc: field of a message receives a copy of that message when you send it. But, bcc: recipients are invisible to all the other recipients of the message including other bcc: recipients. To add an entry in the bcc: field, click the Add bcc: link under the To: field.

Email body The email body is the main part of an email message. It contains the message’s text, images and other data (such as attachments).

Attachments An email attachment is a computer file sent along with an email message. One or more files can be attached to any email message, and be sent along with it to the recipient. Think! What does the attachment icon look in e-mail programs? All e-mail programs and services are different. However, the standard for the attachment icon is a paper clip icon. Below is a picture of the attach files icon in Google Gmail.

When referring to e-mail, an attachment is a file sent with an e-mail message. An attachment can be a picture, a word document, a movie, a sound file, an Excel document or any other file that requires another program to open it. Attachment is added just by clicking t he attachment icon. By clicking the icon the files in your computer will be open and allow you to search for the file you need to attach then double click it or right click and select to attach it.

            QUESTION 08

Explain practically how can you use your laptop computer for video calling and conferencing? What are the software requirement(s) for video calling and/or conferencing?

VIDEO CALL; is the audio and video communication process which uses a live internet connection between people in different locations. That communication including people such as : A. Family   B.  Friends

VIDEO CONFERENCING; is alive visual connection between two or more people residing in separate location for purpose of communication.

Requirement for video call and conferencing:

•           Video input; web camera or video camera.

•           Audio input; microphone.

•           Audio output; loudspeaker associated with display device.

Software used on video call and conferencing are Skype, Google hangout, viber, imo, facebook messenger, i chat (macbook), tango.

Skype is software that enables the world's conversations. Millions of individuals and businesses use Skype to make free video and voice one-to-one and group calls, send instant messages and share files with other people on Skype. You can use Skype on whatever works best for you – on your mobile, computer or tablet. Skype is free to download and easy to use.

Try Skype today and start adding your friends, family and colleagues. They will not be hard to find; hundreds of millions of people are already using Skype to do all sorts of things together and get communicate easily and pass the needed information.

QUESTION 09

By using multimedia teaching materials describe communication satellites and its types

S

atellite is an artificial body placed in orbit around the earth or moon or other planet in order to collect the information for communication.

A satellite is a solid object which revolves around some body due to the effect of Gravitation force. Satellites are classified into different type based on the purpose and size. The various types of satellite include; weather satellite, communication satellite, navigation satellite, earth observation satellite, astronomical satellite, miniaturized satellite.

In this work by using multimedia teaching materials, the communication satellites and its types are discussed in detailed.

Communication satellites: The communication satellite is a satellite that transmits the signals such as telephone, television, radio, internet signals over long distances.

In satellite communication, signal transferring between the sender and receiver is done with the help of satellite. In this process, the signal which is basically a beam of modulated microwaves is sent towards the satellite. Then the satellite amplifies the signal and sent it back to the receiver’s antenna present on the earth’s surface. So, all the signal transferring is happening in space. Thus this type of communication is known as space communication.

Also satellite communication is the method of transporting information from one place to another using the communication satellite in orbit around the earth. Example, Watching the English premier league every weekend with your friends would have been impossible without it.

Electrical signal is used to transmit the information through the wire. However, electrical signal or electric current is not transmitted wirelessly because air is a pure insulator. Hence, it resists the flow of electric current or electrical signal.

Types of communication satellites

1. Passive satellites.

2. Active satellites.

Passive satellites receive the electromagnetic signal from the source or transmitter and redirect it towards the receiver or destination; They are relay stations in space.  For example if you put a hydrogen balloon which has a metallic coating over it, in the air it is technically becomes a passive satellite.

It is divided into two types (Natural satellite and artificial satellite). A moon is natural satellite of earth. The electromagnetic signal transmitted from the source collides continuously with the atmospheric particles. Because of this continuous collision, the signal strength is reduced. Hence, the receiver will receive a weak signal.

Advantageous of Passive satellite,

a) Low cost

b) Work as a reflector

Disadvantageous of Passive satellite,

i)                    The large attenuation of signals.

ii)                  Earth stations require high power (10kw) to transmit the signals.

iii)                Large Earth station with tracking facilities was expensive.

iv)                Require a large number of satellites accessed randomly by different users.

v)                  Control of satellite not possible from ground.

An active satellite is a satellite that receives the signal from the source, amplifies the signal, and redirects the signal towards the receiver. Have Transponder that provide the action to incoming signal and prevent the interference between two signals. Amplify or modify and retransmitted the signal from the earth. Are satellites which can transmit powe.

These amplified signals are stored in the memory of the satellites, when earth properly faces the satellite. Then the satellite starts sending the signals to earth. Some active satellites also have programming and recording features.  Then these recording can be easily played and watched. Their amplification is done by the receivers themselves (AndersonP.et al(2007).

Advantageous of Active satellite,

       Ø   Require lower power earth station.

       Ø   Not open to random use.

       Ø   Directly controlled by operator from the ground.

Disadvantageous of Active satellite,

v  More expensive because use electronic devices.

v  Require skilled person.

QUESTION 10

Differentiate between cloud storage facilities and cloud backup facilities. Practically show how to use one selected cloud storage and backup facility.

C

loud backup or online backup is designed to make a copy of the files you store on your computer and save this copy on a secure online server. In the event that your laptop is stolen, destroyed, crashes or gets damaged in any other way that leads to the loss or corruption of your original data, you’ll only need to download the software client of the online backup service to your computer, and restore your backed up data to your new computer. These restored files will be the same as your original computer-stored files.

Apart from this backup automation feature, these services also offer what’s called a continuous backup, that is, every edit or change you make to your files gets automatically backed up as well. Online backup services will offer file restoring and file versioning too. If you edit a file that you shouldn’t have, you can go back a number of previous versions of the file. Similarly, if you accidentally delete a file from your computer, you can restore this file within a certain period. Other features may include mirror image backup offered by Carbonate or remote wipe feature offered by Sugar Sync that lets you wipe out data synced to a computer that is subsequently lost or stolen.

With cloud storage services you have to manually select the files you want to upload to the cloud and synced to all of your other devices. If you delete a file or somehow the file gets corrupted, this file can no longer be retrieved (again, the flash drive analogy is quite illustrative!).

With an online storage you can access your files directly in your sync folder a feature typical for Drop box and One Drive, or you can access them online through the host site

As a person may have already concluded from reading all of the above, the main difference between a cloud storage and a cloud backup is their purpose or finality – cloud backups are meant for automatically and continuously keeping all of your files safe, while cloud storage solutions are primarily used for storing a number of files always defined by the user, and as a collaborative tool via their excellent sharing capabilities.

Apart from this main and crucial distinction, the following differences also apply:

• Automatic versus manual saving of data – cloud backup services like Just Cloud work automatically, that is, they automatically save and sync all your files that are stored on your computer. Cloud storage services like Drop box only save and sync the files that you’ve manually added to your sync folder;

• Security – cloud backup services are very serious about security, thus, they encrypt files both on transfer and on storage with the latest in encryption technologies (256-bit AES encryption, TSL), and some services like Carbonate will even allow you to manage your own encryption key. This level of security makes sharing and collaboration features much more limited and file preview features much more tedious (files have to be decrypted before you can view them) than in the case of cloud storage services that usually only encrypt files on their servers without locally encrypting them on your computer;

• Redundancy – online storage services don’t offer the same file redundancy offered by online backups. If a file is deleted or overwritten, the change will appear on all synced devices usually without the possibility to restore previous versions of a file or restore the backup of a file. An online backup service will retain several versions of a file and allow you to recover even deleted files. This file versioning and deleted file recovery feature may be available at some cloud storage providers as well (e.g. Drop box), but only in higher tier plans or only as an add-on service, while online backups contain these feature as a core element of their service.

Procedures for opening and storing data in cloud storage facilities

a)      Searching a sample cloud storage facility using search engine.

b)      Sign in if you do not have an account and log in if you have an account.

c)      To add any data to drop box go to file then upload file.

d)      It will come  note asking you choose a file from your device.

e)      After clicking CHOOSE FILE then you has choose file you want to store in drop box.