Saturday 27 August 2022

Chapter 3rd (Computer Networks)





Computer networks are the base of

communication in Information Technology.These are used in a variety of ways and these can include different types of network. In simple words, a computer network is a set of

computers that are connected together (using a media) in a way that they can share information and complete the process.



To share our files or information from

our computer to another computer we need Computer networking. In simple terms Networking means communication and sharing. We can say that a networking means to communicate and sharing an information over a network. In our routine work we use the things

or services where networking plays an important role:

Communicating using email, video, instant messaging.


Other methods sharing devices such as printers, scamers and photocopiers.


Sharing files, sharing software and operating programs on remote systems


Allowing network users to easily access and maintain information



OSI stands for Open Systems Interconnection. It has been developed by ISO - ‘International Organization of Standardization’, in the year 1984. It is 7-layer architecture, with each layer having specific functionality to perform. All these 7 layers work collaboratively to transmit the data

from one person to another across the globe.As we have studied that there are the seven OSI layers. Each layer has different functions.


A list of seven layers are given below:

i, Physical Layer

ii. Data-Link Layer

ili. Network Layer

iv. Transport Layer

v. Session Layer

vi. Presentation Layer

vii. Application Layer


i. Poysical Layer : The main function of this layer is to transmit the individual bits (0,1)from one node(any physical device) to another node. It is the lowest layer of the OSI model. It

establishes, maintains and deactivates the physical connection in a network.


ii. Data-Link Layer : Data-Link layer is responsible for transferring of data frames (a sequence of bits or symbols) without any error. It defines the format of the data on the network.

It provides a reliable and efficient communication between two or more devices. It is mainly responsible for the unique identification of each device that resides on a local network.


iii. Network Layer : Network Layer manages device addressing, tracking the location of devices on the network. It determines the best path to move data from source to the destination

based on the network conditions, the priority of service, and other factors. The Data link layer is responsible for routing and forwarding the packets, The protocols used to route the network

traffic are known as Network layer protocols. Examples of protocols are IP and Ipv6.


iv. Transport Layer : The Transport layer ensures that messages are transmitted in the order in which they are sent and there is no duplication of data. The main responsibility of the

transport layer is to transfer the data completely. It receives the data from the upper layer and converts them into smaller units known as segments. This layer can be termed as an end-to-end

layer as it provides a point-to-point connection between source and destination to deliver the data reliably.


v. Session Layer : The session layer is the fifth layer, which controls the connections between multiple computers. The session layer tracks the dialogs between two processes which can be either half-duplex or full-duplex, which are also called sessions. Session layer adds some checkpoints when transmitting the data in a sequence, If some error occurs in the middle

of the transmission of data, then the transmission takes place again from the checkpoint. This process is known as Synchronization and recovery.


vi. Presentation Layer : A Presentation layer is mainly concemed with the syntax and semantics of the information exchanged between the two systems, It acts as a data translator for a network. This layer is a part of the operating system that converts the data from one presentation format to another format, The Presentation layer is also known as the syntax layer.


vii. Application Layer : An application layer serves as a window for users and application processes to access network service. It handles issues such as network transparency, resource

allocation, etc. An application layer is not an application, but it performs the application layer functions. This layer provides the network services to the end-users.



We have already studied about computer network and OSI layers. Now we will study about the devices that are used in a Network. In simple terms Network Devices are termed the hardware used in making a network. The networks can be as small as used in office or home

and some are as big as often used in big buildings etc. Devices that filter data traffic are called Connectivity Devices.Let's study about various types of Network Devices in detail:


3.4.1 Hub

A network hub is a node that is used to broadcast data to every computer or to an Ethernet-based device connected to it. A hub is basically a multiport repeater. Wires coming from different devices are connected to a Hub. A Hub cannot filter the data so data

packets are sent to all connected devices.In a computer network the hubs are categorized in three types such as:


Active Hub : These hubs regenerate our signals as well as amplify the signal. These are used to extend the maximum distance between nodes on a network.


Passive Hub : These hubs simply distribute the signal coming from the previous ports. These hubs relay signals onto the network without cleaning and boosting them and can't be used to extend the distance between nodes,


Intelligence hub : It is an advanced version of hub and it comprises both active and passive hubs, it provides the ability to manage the network from one central location.This also helps the administrator to monitor network traffic and you can configure each port on it individually, due to this advantage it is also known as a manageable hub.


3.4.2 Switch

It is a small device that is used to

transfer data packets between multiple network devices such as computers,

routers, servers or other switches. In simple words a switch works like a

multiport bridge, it has a buffer that is used to boost its efficiency and

performance of a switch The switch can also perform any type of error-checking

before forwarding the data, this advantage makes it very efficient as it does not forward packets that have errors and forward good packets selectively to correct port only.



3.4.3 Routers

Router is also an important hardware device and it works as a gateway of networks responsible for keeping data flowing between networks and also keep networks connected to the Internet. Moreover a router is a device like a switch that routes data packets based on their IP addresses, Router is mainly a Network Layer device.


Functions of a Router : The router basically performs two major functions:


Forwarding : Router receives the packets from its input ports, checks it header information and looks up to the routing table to find the appropriate output port to dump the packets.


Routing : Itis the process by which the router determines that what would be the best path for the packet to reach at the destination without any loss of information.


3.4.4 Repeater

A repeater is a network device that is used for regenerating the signal and then transmit. It regenerate the signal over the same network before the signal

becomes too weak or gets corupted. The repeaters do not amplify the signal because when the signal becomes weak, they copy the signal bit by bit and

regenerate it at the original strength. A repeater is only a 2 port Network Device.


3.4.5 Bridge

A bridge is such type of device that can be used in computer networks to interconnect two LANs together and other separate network segments.It uses the MAC address information in

forwarding data packets. Only the data that needs to be sent across the bridge to the next network segment is forwarded. It has a single input and single output port.


Types of Bridges :

Transparent Basic Bridge : This bridge is the simplest type of bridge. Actually it stays transparent or invisible to the other devices on the network. Transparent bridge

can store data briefly(the details of its source and destination) before forwarding to the next network.


Source Routing Bridge : In these bridges, routing operation is performed by source station and the frame specifies which route to follow. This data is transferred by sending a special frame called discovery frame, which spreads through the entire

network using all possible paths to destination.


3.4.6 Gateway

A gateway is a component that is part of two networks, These networks use different protocols. The gateway translates one protocol into the other. Therefore gateway is also called

protocol converter and can operate at any network layer. The activity of a gateway is more complex than that of the router or switch because router and switch communicates using more than one protocol.For basic Internet connections at home, the gateway is the Internet Service Provider that gives you

access to the entire Internet.


3.4.7 Brouter

A Brouter is a combination of a Bridge and a Router. It functions like a bridge and a router.A Brouter connects the networks which use different protocols. It can be programmed to work

only as a bridge or only as a router. Working as router, it is capable of routing packets across networks and working as bridge, it is capable of filtering local area network traffic.



The word communication defines the tool or the means of delivering and receiving data or information such as Telecommunication. In  telecommunication, these means are transmission and storage tools or channels for data storage and transmission. Various transmission media can be used for transfer of data, These transmission media may be of two types:

Guided Media

Unguided Media

Let's study about various types of transmission media in brief:


3.5.1 Guided Media

In guided media the data is transmitted using cabling system that has a fixed path. For example, copper wires, fiber optic wires, etc. Twisted Pair Cable : A twisted pair cable contains two separate insulated copper wires,which are twisted together and it run in parallel.One of the wires is used to transmit data and the other is the ground reference.The two insulated

copper wires are twisted around each other just to reduce crosstalk or electromagnetic induction between these pairs of wires.


There are two types of twisted pair cables:

Unshielded Twisted Pair (UTP) : These generally comprise of wires and insulators.


Shielded Twisted Pair (STP) : They have a braided wired mesh that encases each pair of Twisted pair comes with each pair uniquely colour coded when it is packaged in multiple pairs. For

different purposes such as analog, digital and Ethernet,different pair is required.Copper wires are the most common wires used for transmitting signals because of good performance at low costs.Advantages of twisted pair cable : The twisted pair cable is the oldest one used and most popular cables all over the world. they offer such as:


These cables can be used both for analog and digital transmissions.


Least expensive for short distances.


Entire network does not go down if a part of network is damaged.


Disadvantages of twisted pair cable : With its many advantages, twisted pair cables offer some disadvantages too such as:-

The Signal cannot travel long distances without using repeaters


High error rate for distances greater than 100m


Very thin and hence breaks easily and not suitable for broadband connections Coaxial Cable : Coaxial

cable is a two conductor electrical cable consisting of a centre conductor and an outer conductor with an insulating spacer between the two. Coaxial cables are copper cables with better shielding than twisted pair cables, so that transmitted signals may travel longer distances at higher speeds, A coaxial cable consists of these layers, starting from the innermost :

1. Core wire is of stiff copper material, so it's not easy to bend it if necessary.


2. Insulating material surrounding the core


3. Closely woven braided mesh of conducting material surrounding the insulator The coaxial cables are widely used for cable TV connections and LANs.


Advantages of Coaxial Cables :

No effect on signals of disturbance from outer side.


Thick coaxial cable has an extra protective plastic cover that help to keep moisture away.


Can be used for both analog and digital signals.


Easy to install and maintain.


Disadvantages of Coaxial Cables :

These cables are expensive as compared to twisted pair cables.


These are not compatible with twisted pair cables.


Thick coaxial is that it does not bend easily and is difficult to install.


3.5.L3 Optical Fibre : An optical fibre cable has a number of optical

fibres (a thin flexible fibre with a glass core) bundled together which are

normally covered in plastic covers or shields. Optical cables are used to

transfer digital data signals in the form of light up to the distances of hundreds of miles with a higher throughput rates in comparison to other electrical communication cables.


Optical fibre cable is widely used in fibre optic communications. Light Emitting Diodes (LEDs) or Laser Diodes (LDs) emit light waves at the source, which is read by a detector at the

other end, All optical fibres use a core of hair-like transparent silicon covered with less refractive indexed cladding. Optical fibres are very sensitive So, it is normally covered with a high-strength, lightweight protective material. Each fibre is made up of these three layers,starting with the innermost layer ?


Core made of high quality silica glass or plastic


Cladding made of high quality silica glass or plastic.


External protective outer covering called buffer


It must be noted that both core and cladding are made of similar material. However, as refractive index (the ratio of the velocity of light in a vacuum to its velocity in a specified medium.) of the cladding is lower and any light wave distracted from core is reflected back due to total internal reflection.


Advantages of Optical Fibre : Optical fibre is fast replacing copper wires because of these advantages that it offers ?


One single mode fibre can replace a wire made of heavy and large copper.


Higher bandwidth.


Suitable for industrial and noisy areas.


Data Signals can be sent to a long distance without weakening.


Disadvantages of Optical Fibre: Despite long segment lengths and high bandwidth,using optical fibre may not be a viable option for every one due to these disadvantages :

Optical fibre cables are expensive.


The optical fiber are highly polished to allow light to pass with a little loss.


Light waves are unidirectional, so two frequencies are required for full duplex transmission.



3.5.2. Unguided Media

The media that doesn't use any type of directed or guided media is called unguided media.Unguided media transfer the data using electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication. Signals are normally broadcast using through free space(or in a few cases, water) and thus are available

to anyone who has a device capable of receiving them.


We can categorize wireless transmission into the following groups:





Radio Waves

Micro waves



Let's study all of these in detail as below: Infrared : Infrared (IR) is a type of wireless mobile technology that is used for communication over a short range of field. IR communication has some major limitations such as it requires line-of-sight, has a short transmission range and is unable to penetrate through walls.


IR cannot be used for long - range communication. Because Its use is limited within a closed space and they do not need any government permissions for their applications.


Applications of Infrared Waves in Communications:

Remote controls for television, stereos and other home appliances.


Wireless LANs

Wireless modem, keyboard, mouse, printer etc

Fire detectors

Night vision systems

Intrusion detection systems

Motion detectors NFC (Near Field Communication)

: NFC technology is a new technology that is used for data transfer. It is a contactless way in which NFC devices interact also bears similarity to Bluetooth It can be employed in contactless payment systems. It also provides a compact way to communicate information, which may be used for advertising or social media purposes.


NFC tags or cards are passive devices. They store data that can be retrieved by active NFC devices. The most common example of NFC use involves a contactless payment system, in

which a smartphone can be swiped at an NFC reader (which are increasingly being installed Dear a store's cash register) to make a contactless payment. The NFC device transmits information about the smartphone user's credit card, In this case, the reader is the NFC tag, while the smartphone acts as an NFC device. Because NFC must occur within short range, the transaction is considered secure. Bluetooth : Bluetooth is a type of radio communication technology that enables a low-power and a short distance wireless networking between phones, computers and other network devices.Two Bluetooth devices are connected to each other while using a process called pairing. When you press a button or select a menu option on the unit, a Bluetooth device initiates a new connection. The pairing details may vary depending on the type of device. PCs and other devices can also be enabled through the use of Bluetooth dongles. Bluetooth networks use a dynamic topology called Piconet.

Bluetooth cover only short distances, typically up to 30 feet until the most recent standard Wi-Fi : Wi-Fi is one of a popular wireless networking technology. Wi-Fi stands for “wireless fidelity". It is commonly called as wireless LAN (local area network). Wi-Fi allows local area networks to operate without cable and wiring. It is becoming

popular choice for home and business networks, By using this technology we can exchange the information between two or more devices that are of same network.


Wi-Fi has been developed for mobile computing devices, such has laptops, but it is now using for mobile applications and consumer electronics like televisions, DVD players and even in digital cameras. Radio waves : Radio waves are

a type of electromagnetic waves. These waves are famous for their use in communication technologies, such as television, mobile phones and radios. These devices receive radio waves and convert them to mechanical

vibrations in the speaker to create sound waves. When an antenna transports radio waves they are propagated in all the directions in free space.


It means that, the sending and receiving antennas do not have to be aligned. The frequency refers to number of waves per second, it is measured in hertz (Hz).


Applications of Radio waves:

Radio waves are useful for multicasting in case where one sender but have many



Examples of radio waves are television, AM and FM radio, cordless phones, and



Advantages and disadvantages of Radio waves:

Radio waves are very powerful waves. These waves are easy to generate and penetrate through buildings. These waves also can travel at long distances, Radio waves cover a large

area. Micro Waves : Another important type of waves is microwave. Microwave is defined as the part of the electromagnetic spectrum (It is a type of light, that a human eye can't

see it) with large infrared waves and short radio waves. An example of microwave is a type of cooking that uses energy waves to cook food i.e. microwave cooking. If we talk about the word Microwave then the prefix "micro-" indicates that microwaves are "small" because they have shorter wavelengths as compared to waves used in typical radio broadcasting.


Microwave Transmission is classified in two categories as follows:

Terrestrial Microwave

Satellite Microwave


Applications of Micro Waves : Due to the unidirectional properties of Micro Waves, they are very useful when unicast (one-to-one) communication is needed between the sender and

the receiver. Cellular phones, satellite networks, and wireless LANs are using Micro Waves.


Advantages of microwaves ;: Microwaves are inexpensive for short distance as it requires a higher tower for a longer distance.


Microwave transmission is cheaper than using cables.


Microwave transmission provides easy communication.


Disadvantages of microwaves:

Bandwidth is limited in microwave transmission.


Asignal can be moved out of phase and any environmental change such as rain, wind can distort the signal so these signals are susceptible to weather conditions. Terrestrial Microwave : These microwave transmission are sent between two microwave stations situated on earth. It is the most common form of long distance communication. Satellite Microwave : A satellite is an entity that revolves around the earth at a certain height. Satellite communication offers more flexibility than fibre optic and cable

systems. We can transmit signals from any point on the globe by using satellite transmission.


Advantages of Satellite Microwave:

Coverage of Satellite Microwave is more that Ground Microwave.


It is used in a variety of applications such as radio/TV signal broadcasting, weather forecasting, radio/TV signal broadcasting, mobile communication etc.


Disadvantages of Satellite Microwave:

The manufacturing cost is very high of satellite and very expensive to launch a satellite.


Transmission can go down in bad weather.



Communication mode is also called theTransmission Modes. The mechanism of transferring data or information between two linked devices connected over a network is referred to as

Transmission Modes. It tells the direction of signal flow between the two linked devices.Categories of Transmission Modes: There are three categories of transmission mode:

3.6.1 Simplex Mode

3.6.2 Half-Duplex Mode

3.63 Full-Duplex Mode


3.6.1 Simplex Mode

In this type of transmission mode, communication is unidirectional that is data can be sent only in one direction. This means you cannot send a message back to the sender just like a one- way street.

From the two devices, only one can send or transmit on a link and the other can only receive the data,


Example : A simplex transmission can be seen between a computer and a keyboard a signal is sent from a keyboard but no signal can't be sent back to keyboard. A television broadcast, television and remote sare also examples of simplex transmission.


Advantage of Simplex mode:

In this mode, the station can utilize the entire capacity of the communication channel,so there can be transmitted more data at a time.


Disadvantage of Simplex mode:

Mainly communications require the two-way exchange of data but it is unidirectional,so it has no inter-communication between devices,



3.6.2 Half-Duplex Mode

In a Half-duplex mode, each station can transmit and receive the data as well. The flow of messages can be in both directions, but not simultaneously, The entire capacity (bandwidth) of the communication channel is utilized

in one direction at a time. In half-duplex mode, the sender sends data and wait for its acknowledgment and if there is any error so that receiver can demand it to retransmit that data, By this error detection is possible.


An example of half-duplex mode

is Walkie-talkic. In Walkie-talkic, from one side a speaker speaks, and from the other side, someone listens. After a pause, the other speaks and first-person listens.


Advantage of Half-duplex mode:

In half-duplex mode, the entire capacity of a channel is taken over by whichever of the two devices is transmitting at the same time.


Disadvantage of Half-Duplex mode:

It causes the delay in sending the data at the correct time as when one device is sending the data, then another has to wait to send data.


3.6.3 Full Duplex Mode

In Full duplex mode, the communication is bi-directional, i.¢., the data flow in both the directions at the same time.


From both the ends receipt and transmission of data is possible at the same time. Full-duplex mode has two physically separate transmission paths.It is one of the fastest mode of communication between devices,


Example : On a mobile phone, two people sare communicating with each other both can talk and listen to each other at the same time, this is the full-duplex transmission.


Advantage of Full-duplex mode:

Both the stations can send and receive the data at the same time, so the capacity of link can be shared.


Disadvantage of Full-duplex mode:

The bandwidth of the communication channel is divided into two parts if there is no dedicated path exists between the devices.



Network sharing is a feature of a network that allows resources to be shared over a network, that can be files, documents, folders,media, etc. These are made accessible to other users/computers over a network.


Network sharing enables access to

information by more than one person through more than one device at the same or at different times. By connecting a device to a network, other users/devices in the network can share and exchange information through this network, Network sharing is also known as shared resources,


3.7.1 Printer Sharing

Printer sharing is the process of allowing multiple computers and devices connected to the same network to access one or more printers. Each node or device on the network can print to

apy shared printer and, to some extent, make changes to the printer settings, depending on the permissions set by the administrator for each user.If a printer is attached to a computer that supports printer sharing, the computer can share that printer with other computers on the same network, It does not matter whether the shared

printer is old or new.


How to share a printer:

From the Control Panel, open Devices and Printers.


Right-click the printer you want to share. Click Printer Properties, and then select the Sharing tab.


Check Share this Printer. Under Share name, select a shared name to identify the printer. Click OK.



Network Protocols are a set of rules governing exchange of information in an easy, reliable and secure way. Before we discuss the most common protocols used to transmit and receive

data over a network, we need to understand how a network is logically organized or designed.The most popular model used to establish open communication between two systems is the Open Systems Interface (OSI) model proposed by ISO.


3.8.1 TCP/IP

TCPAP stands for Transmission Control Protocol/Internet Protocol. TCP/IP is a set of layered protocols used for communication over the Internet. Its communication model is,client-server model. A computer that sends a request is the client and a computer to which the request is sent is the server.


TCP/IP bas four layers:

Application layer : Application layer protocols like HTTP and FTP are used.


Transport layer : Data is transmitted in the form of datagrams using the

Transmission Control Protocol (TCP). TCP is responsible for breaking up data at the client side and then reassembling it on the server side.


Network layer : Network layer connection is established using Internet Protocol (IP)at the network layer. Every machine connected to the Internet is assigned an address

called IP address by the protocol to easily identify source and destination machines.


Data link layer : The data link layer is called the second layer of Open System Interconnection or OSI. It is responsible for transmitting the data within a Physical network link. It is considered the most reliable system for transmitting data from one node to another node.


3.8.2 FTP

FTP stands for File Transfer Protocol. It is used to transfer large number of files between the computers or over the network. The protocol that handles these requests is File Transfer

Protocol or FTP.


3.8.3 PPP

Point to Point Protocol or PPP is a data link layer protocol that enables transmission of TCP/IP traffic over serial connection, like telephone line. Using PPP, home users can avail

Internet connection over telephone lines,


3.8.4 SMTP

SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving e-mail. However, since it is limited in its ability to queue messages at the receiving end, it is

usually used with one of two other protocols, POP3 (Post Office Protocol) or IMAP (Internet Message Access Protocol), that let the user save messages in a server mailbox and download them periodically from the server. In other words, users typically use a program that uses SMTP for sending e-mail and either POP3 or IMAP for receiving e-mail.


3.8.5 POP/IMAP

Post Office Protocol version (POP3) is a standard mail protocol used to receive emails from a remote server to a local email client. POP allows you to download email messages on your local computer and read them even when you are offline. Note, that when you use POP to connect to your email account, messages ate downloaded locally and removed from the email server. This means that if you access your account from multiple locations, which may not be the best option for you. On the other hand, if you use POP, your messages are stored on your local computer, which reduces the space your email account uses on your web server.


The Internet Message Access Protocol (IMAP) is a mail protocol used for accessing email on a remote web server from a local client. IMAP and POP3 are the two most commonly used Internet mail protocols for retrieving emails. Both protecols are supported by all modern email clients and web servers.


POP protocol provides the facility to access email only from one application there as IMAP allows simultaneous access by multiple clients. This is why IMAP is more suitable for you if you're going to access your email from different locations or if your messages are managed by multiple users.


3.8.6 HTTP

HTTP means Hypertext Transfer Protocol. HTTP is the underlying protocol used by the World Wide Web and this protocol defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For

example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page. The other main standard

that controls how the World Wide Web works is HTML, which covers how Web pages are formatted and displayed.



3.9.1 MAC Address

Stands for “Media Access Control Address," and it does not referred to Macintosh Computers. A MAC address is a hardware identification number that uniquely identifies each device on a network. The MAC address is manufactured into every network card, such as an Ethernet card or Wi-Fi card, and therefore it cannot be changed. Because there are millions of

Network-enabled devices are in world and each device has its own Unique MAC address. For this each MAC address is designed using 6 different two hexadecimal characters separated

with colon,For example, an Ethernet card may have a MAC address of 00:00:0A:BB:28:FC. You do not need to know this address, as is automatically recognized by most networks.


3.9.2 IP Address

Every machine on a network has a unique identifier. Just as you would address a letter to send in the mail, computers use the unique identifier to send data to specific computers on a network. Most networks today, including all computers on the Internet, use the TCP/IP protocol as the standard for how to communicate on the network. In the TCP/IP protocol, the unique identifier for a computer is called its IP address,


There are two standards for IP addresses: IP Version 4 (IPv4) and IP Version 6 (IPv6). All computers with IP addresses have an IPv4 address, and many are starting to use the new IPv6

address system as well. Here's what these two address types mean:


IPv4 uses 32 binary bits to create a single unique address on the network. An IPv4 address is expressed by four numbers separated by dots. Each number is the decimal (base-10)representation for an eight-digit binary (base-2) number, also called an octet. For example:


IPv6 uses 128 binary bits to create a single unique address on the network, An IPv6 address is expressed by eight groups of hexadecimal (base-16) numbers separated by colons.



1. A computer network is a set of computers that are connected together.


2. The devices that filter traffic are called connectivity devices


3. A repeater is a network device that is used for regenerating the signal and transmitting.


4. A hub is basically a multiport repeater,


5. In a computer network, the hubs are categorized in three types such as; Active Hub,Passive Hub and Intelligence Hub


6. Ina network, a Bridge is a device that is used to connect two separate Ethernet networks into one extended Ethemet.


7. A Bridge is a2 port device.


8. A switch is like a multiport bridge with a buffer that can boost its efficiency and performance.


9. A router is a device like a switch that routes data packets based on their IP addresses.


10. A Brouter is a combination of a Bridge and a Router.


11. Transmission media is of two types: Guided and Un-guided.


12. Optical cables are used to transfer digital data signals in the form of light up to the distances of hundreds of miles.


13. The media that doesn't use any type of directed or guided media is called unguided media,


14. Two Bluetooth devices are connected to each other while using a process called


15. Microwave Transmission is classified in two categories as follows: such as Terrestrial

Microwave and Satellite Microwave.


16. Satellite communication offers more flexibility than fiber optic and cable systems.


17. Communication mode is also called the Transmission Modes.


18. There are three categories of transmission mode: Simplex Mode, Half-Duplex Mode and Full-Duplex Mode


19. Network sharing is a feature of a network that allows resources to be shared over a network, they can be files, documents, folders, media, etc.


20. Network Protocols are a set of rules governing exchange of information in an easy,reliable and secure way.






1. Multiple Choice Questions:

1. A computer is a set of computers that are connected together.

a. Network

b. System

c. Protocol

d, Internet


2 A______is basically a multiport repeater.

a. Hub

b. Switch

c. Router

d. Bridge


3. A is a 2 port device.

a, Hub

b. Switch

c. Router

d. Bridge


4. Wi-Fi stands for.

a. Wireless Field

b. Wireless Fidelity

c. Wire Fire

d. Wire Fidelity


5. OA is a combination of a Bridge and a Router.

a. Switch

b. Bridge

c, Hub

d,  Brouter


2. Write Full Forms






3. Short Answer Type Questions. (Write the answers in 4-5 lines)

1. What is a Network?

2 Write different types of OSI layers.

3. What is a Bridge?

4. Why do we need a network?

5. What is guided media?

6. What is un-guided media?

7. Define Protocol.



5. Long Answer Type Questions. (Write the answers in 10-15 lines)

1. What are network devices? Describe any three network devices.

2 What is Unguided Media. Write any two media.

3 What is a twisted pair cable? Define its advantages and disadvantages.

4. What is Fibre Optic Cable? Define its advantages and disadvantages.

5. What is Communication Mode? Define its types.



1. Draw a chat to represent different types of Communication Media.

2. Draw a chart to represent different types of Network Devices.