8th Computer Networks and Communications Unit-01

Q1. Tick the correct choice for the following questions.

i. A computer network is interconnection of two or more ____________________________.

a. Printers

b. Monitors

c. Computers (Correct Answer)

d. Hard disks

ii. The data is transferred from one place to another through ____________________________.

a. Mouse

b. Keyboard

c. Storage device

d. Transmission media (Correct Answer)

iii. Which of the following is a communication device?

a. Mouse

b. Modem (Correct Answer)

c. Monitor

d. Printer

iv. Which device is used to send messages, data or information to other device?

a. Receiving device

b. Sending device (Correct Answer)

c. Communication device

d. Input device

v. Which of the following network is confined to a relatively small area?

a. Internet

b. WAN

c. MAN

d. LAN (Correct Answer)

vi. In WAN, “W” stand for____________________________.

a. Width

b. Wire

c. Wide (Correct Answer)

d. Whole

vii. Which is a powerful computer that facilitates the whole network by providing variety of services to the computer or devices connected to the network

a. Server (Correct Answer)

b. Client

c. PC

d. Laptop

viii. ____________________________is an expansion card that enables a computer to connect to a network.

a. Network Interface Card (NIC) (Correct Answer)

b. VGA Card

c. FAX Card

d. Sound Card

ix. ____________________________is a type of wire that consists of a center wire surrounded by insulation and then a grounded shield of braided wire.

a. Fiber Optic

b. UTP

c. STP

d. Coaxial cable (Correct Answer)

x. Which of the following is the fastest transmission media?

a. UTP cable

b. STP cable

c. Fiber Optic cable (Correct Answer)

d. Coaxial cable

Q2. Fill in the blanks.

i. A computer network consists of ____________________________ basic components.

Answer: Four

ii. In a computer network a ____________________________ device receives messages, data or information from a sending device.

Answer: Receiving

iii. ____________________________ is the channel or path through which the data or information is transferred from one place to another in a computer network.

Answer: Transmission media

iv. ____________________________ is a less powerful computer as compared to a server computer that relies on servers for resources.

Answer: Client

v. MAN stands for ________________________________________________________.

Answer: Metropolitan Area Network

vi. ____________________________ is a very large computer network covering a large geographic area, such as state, province, country or the whole world.

Answer: Wide Area Network (WAN)

vii. NIC stands for ________________________________________________________.

Answer: Network Interface Card

viii. ____________________________is a wireless technology for exchanging data between different devices over short distances.

Answer: Bluetooth

ix. ____________________________is a type of cable that uses glass (or plastic) threads to transmit data.

Answer: Fiber Optic

x. ____________________________is global navigation satellite system.

Answer: Global Positioning System (GPS)

Q3. Match Column A with Column B.

Q4. Give brief answers to the following questions.

i. Define the following terms:

a. Data Communication: Data communication is the exchange of data between two or more devices through some form of transmission media, such as cable wire, or wireless.

b. Cellular Communication: Cellular communication is a radio communication that offers communication services to thousands of cell phone users around the globe.

c. Satellite Communication: Satellite Communication is a form of wireless communication in which satellites are ideally placed to provide telecommunication links between different places across the globe. These satellites enable us to communicate over a large distance.

d. Fiber optic cable: Fiber Optic cable uses glass or plastic threads to transmit data, which transmit data in the form of light waves.

ii. Name different types of transmission media.

There are three types of transmission media.

Twisted pair cable
Coaxial cable
Fiber optic cable

iii. How a Modem works? Show diagrammatically.

A dial-up MODEM (Modulator-Demodulator) is a communication device. It is used to connect to the Internet, exchange information, and to send and receive data from one computer to the other. It translates computer information into a form that can be transmitted over telephone lines.

A Modem can be located inside or outside the computer.

In computers, information is stored digitally, whereas information transmitted over telephone lines is in the form of analog signals. The modem converts digital signals (called Modulation) and then analog signals to digital signals (called Demodulation).

Diagrammatically, Modem works can be shown as below.

iv. Differentiate between LAN and WAN.

A Local Area Network (LAN) is a network that is confined to a relatively small area like a building or office while a Wide Area Network (WAN) is a very large computer network covering a large geographical area, such as a state, province, country or the whole world.

v. What is Satellite Communication?

Satellite communication is a form of wireless communication in which satellites are ideally placed to provide telecommunication links between different places across the globe. These satellites enable us to communicate over a large distance.

Satellite communication can be used for many applications such as international telephone calls, providing communication to remote areas of earth, ships, aircraft and other mobile vehicles.

Q5. Give detailed answers to the following questions.

i. Explain different types of physical transmission media.

The means through which data is transferred from one place to another is called transmission or communication media. There are three common types of physical transmission media or guided media.

There are three types of transmission media.

Twisted Pair Cable
Twisted pair cable is the most popular transmission media for transferring data on a computer network. They are especially used in Local Area Network. Twisted pair wires consist of two strands of copper twisted together.
Twisted pair cable is of two types:
- Unshielded Twisted Pair (UTP)

If the wires are unshielded, they are called Unshielded Twisted Pair cables.

- Shielded Twisted Pair (STP)

If the wires are shielded, they are called Shielded Twisted Pair cables.

Characteristics of Twisted Pair Cables

- It is the least expensive type of cable.
- It is easy to install.

Coaxial Cable

A type of wire that consists of a center wire surrounded by insulation and a shield of braided wire. The shield minimizes electrical and radio frequency interference.

Coaxial cabling is the primary type of cabling used by the cable television industry, and is also widely used for computer networks. Plastic jacket, insulator, and braided shield in a coaxial cable ensure data transmission without interference from other cables.

Characteristics of Coaxial Cable

- It is more expensive than standard telephone wire.
- It is much at risk of interference than twisted pair cable.
- Its data transfer rate is higher than twisted pair cable.
- It is easy to install.

Fiber Optic Cable

Fiber Optic cable is a type of cable that uses glass or plastic threads to transmit data. It consists of a bundle of glass threads, each of which is capable of transmitting messages in the form of light waves.

Fiber Optic cable consists of a center glass core surrounded by several layers of protective material such as cladding and buffer coating.

Characteristics of Fiber Optic cable

- It is more expensive as compared to other cables.
- It is difficult to install.
- The data transfer rate of fiber optic cable is the highest.

ii. Explain different types of computer networks.

On the basis of geographic distance, computer networks are categorized into the following three types:

LAN (Local Area Network)
MAN (Metropolitan Area Network)
WAN (Wide Area Network)

Local Area Network (LAN):

A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a building or adjacent buildings. LAN is the most common type of network and is usually owned by one organization.

Advantages of LAN

- Computers can share peripheral devices like printers, storage device, scanning devices, CD-ROM etc.
- User can save their work centrally on the network server.
- User can communicate with each other and transfer data between computers very easily. Application package such as a word processor, spreadsheet etc. in the server computer can be shared by all users.

Disadvantages of LAN

- Special security measures are needed to stop unauthorized users.
- LAN need to be maintained by skilled personnel.

Metropolitan Area Network (MAN)

A large computer network which extends to a city or to a metropolitan region is termed as Metropolitan Area Network or MAN. A MAN connects two or more LAN to form a network spread over the whole city.

Cable television network in a city is a good example of MAN.

Advantages of MAN

- It is bigger than LAN.
- It transfers data at high speed.

Disadvantages of MAN

- It is expensive.
- It is difficult to maintain.

Wide Area Network (WAN)

Wide Area Network is a very large computer network covering a large geographical area, such as a state, province, country or the entire world. WAN often connect multiple smaller networks. Many large organizations develop their own private WAN’s. An example of WAN is Internet.

Advantages of WAN

- In WAN, the users at different locations are connected to a central server.
- It is used to monitor distant locations and offices.

Disadvantages of WAN

- Setting up a network can be an expensive and complicate task.
- Management, maintenance and troubleshooting WAN is a difficult task.
- Security is a big issue.

iii. Describe the following cutting edge technologies.

a. GPS (Global Positioning System)

Global Positioning System (GPS) is a global navigation satellite system. This position-finding system uses satellites to determine precise location on the surface of the Earth.

GPS can be used to pinpoint any ship or submarine on the ocean, or to measure the height of Mount Everest. It can also be used by armed forces, scientists, fishermen, climbers, hikers and anyone who wants the accurate location and time information. For example, a stolen vehicle can be detected through Global Positioning System (GPS).

b. Bluetooth

Bluetooth is a wireless technology for exchanging data between different devices over short distance. It can connect several devices to communicate with each other wirelessly.

Networks are usually formed temporarily from portable devices such as cellular phones, handhelds computers and laptops.

Bluetooth offers service like file sharing, voice transport and for connecting devices like mouse, keyboard etc.

iv. Discuss different component of a computer network.

A computer network consists of the following four basic components:

Sending Device

A device which is used to send messages, data or information to other device connected to a network is called a sending device. Usually, a sending device can be a computer or mobile.

Receiving Device

In a computer network, a receiving device receives messages, data or information from a sending device. The receiving device could be a computer, printer, fax machine or a storage device.

Communication Devices

Communication devices are used for communication between the computers and other devices. Modem is a popular communication device which is used for Internet communication.

Transmission Media

Transmission Media is the channel or path through which the data or information is transferred from one place to another in a computer network. Networks are connected by wire or wireless transmission medium.

v. What are communication devices? Explain any two of them.

Most commonly used communication devices are:

Dialup Modem

A Dialup Modem, called Modulator-Demodulator and is a communication device. It is used to connect to the Internet, exchange information, and to send and receive data from one computer to the other computer. It translates computer information into a form that can be transmitted over telephone lines.

In computers, information is stored digitally, whereas information transmitted over a telephone line is in the form of analog signals. Modem converts digital signals (Modulation) and then analog signals to digital signals (Demodulation).

Network Interface Card (NIC)

Network Interface Card (NIC) is an expansion card that enables a computer to connect to a network. Each NIC has a unique serial number. This number is used to identify the computer on the network.

A Network Interface Card (NIC) must be installed in each computer on the network.

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