Plus One Computer Science Chapter Wise Questions and Answers Chapter 11 Computer Networks

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Kerala Plus One Computer Science Chapter Wise Questions and Answers Chapter 11 Computer Networks

Plus One Computer Networks One Mark Questions and Answers

Question 1.
An interconnected collection of autonomous computers is called _________
Answer:
Computer Networks

Question 2.
State true/false
A computer connected to a network is called work station.
Answer:
True

Question 3.
A work station is also called
Answer:
Node

Question 4.
Which hardware is used to connect a work station to a network?
Answer:
Network Interface Card (NIC)

Question 5.
Rules and convention to transmit data on a network is called _________
Answer:
Protocol

Question 6
In your computer lab sometimes you can see that cable from some computers are connected to a small box. What is it?
Answer:
It is a Hub/Switch

Question 7.
The computers connected in your school lab is a _________ type network.
Answer:
Local Area Network

Question 8.
A Cable TV Network that spread over the city is a _________ type network.
Answer:
Metropolitan Area Network

Question 9.
Internet is a __________type network.
Answer:
Wide Area Network

Question 10.
The school management is decided to connect computers in your HSS lab and high school lab located adjacent buildings. Which type of network is this?
Answer:
Local Area Network

Question 11.
A company decided to connect the computers of their branch located in another city away from 10 km. Name this network.
Answer:
Metropolitan Area Network

Question 12.
Geometrical arrangement of computers in a network is called _________
Answer:
Topology

Question 13.
From the following select an ISP.
(a) KSEB
(b) KSRTC
(c) BSNL
(d) PWD
Answer:
(c) BSNL

Question 14.
ISP means
Answer:
Internet service provider

Question 15.
ISDN means
Answer:
Integrated services digital network

Question 16.
State true/false.
In peer to peer configuration all the computers are with equal configuration.
Answer:
True

Question 17.
State true/false.
In client server configuration, a computer is powerful than others.
Answer:
True

Question 18.
Consider the following address.
http://www.nic.kerala.gov.in, “in” is used to represent what?
Answer:
“in” is used to represent the country “India”.

Question 19.
Which top level domain is used for non commercial organisation?
Answer:
org

Question 20.
Which geographical top level domain is used for the country “France”?
Answer:
Fr

Question 21.
DNS stands for.
Answer:
Domain Name System

Question 22.
An IP address consists of bits long.
(a) 4
(b) 16
(c) 32
(d) 64
Answer:
(c) 32 bits

Question 23.
An IP address consists of bytes long.
(a) 4
(b) 16
(c) 32
(d) 64
Answer:
(a) 4 Bytes

Question 24.
From the following which media is using light rays for data transfer.
(a) Twisted pair cable
(b) Optical fibre
(c) Coanial cable
(d) Microwave station
Answer:
(b) Optical fibre

Question 25.
The wiring is not shared in a topology. Which is that topology?
Answer:
Star

Question 26.
________ is a combination of any two or more network topologies.
Answer:
Hybrid Topology

Question 27.
The nodes in a topology with two or more paths. Which topology is this?
Answer:
Mesh topology

Question 28.
Copying the signals from the earth to satellite is called __________
Answer:
Uplink

Question 29.
Copying the signals from the satellite to earth is called ____________
Answer:
Downlink, Mesh topology

Question 30.
In very short distance networks, which communication media is used?
Answer:
Twisted pair cables or coaxial cables.

Question 31.
In long distance networks, which communication medias are used?
Answer:
microwave station, satellites, etc.

Question 32.
From the following which connector is used to connect UTP/STP twisted pair cable to a computer.
(a) RJ – 45
(b) RS – 1
(c) CG – 1
(d) None of these.
Answer:
(a) RJ – 45

Question 33.
The cable media that use light to transmit data signals to very long distance is ________.
Answer:
Optical fibre cable

Question 34.
AM and FM radio broadcast and mobile phones make use of _________ medium for transmission.
Answer:
Radio waves

Question 35.
A short range communication technology that does not require line of sight between communicating device is __________.
Answer:
Wi-Fi

Question 36.
A communication system that is very expensive, but has a large coverage area when compared to other wireless communication system is ______
Answer:
Satellite link

Question 37.
In which topology is every node connected to other nodes?
Answer:
Mesh topology

Question 38.
Any device which is directly connected to a network is generally known as ___________
Answer:
Node or Work station or Client or Terminal

Question 39.
In ____________ topology all the nodes are connected to a main cable. (1)
Answer:
Bus topology

Question 40.
Write the full from of FTTH.
Answer:
Fibre To The Home

Question 41.
Which one of the following statements is TRUE in relation with Wi-MAX Internet connectivity?
(a) make use of satellite connection
(b) Uses cable connection
(c) Uses laser beam for connection
(d) Microwave is used for connectivity
Answer:
(d) Microwave is used for connectivity

Question 42.
Identify the type of LAN topology in which there are more than one path between nodes,
(a) Star
(b) Ring
(c) Mesh
(d) Bus
Answer:
(c) Mesh topology

Question 43.

1. To make data transfer faster, a switch stores two different addresses of all the devices connected to it. Which are they?
2. Name the device that can interconnect two different networks having different protocols.

Answer:

1. IP and MAC address
2. Gateway

Question 44.

1. Different networks with different protocols are connected by a device called ________
   • Router
   • Bridge
   • Switch
   • Gateway
2. Define Protocol

Answer:

1. Gateway
2. Protocol: The rules and conventions for transmitting data.

Plus One Computer Networks Two Mark Questions and Answers

Question 1.
Is it possible to connect all the computers to a network? Justify your answer.
Answer:
No. It is not possible to connect all the computers to a network. A computer, with a hardware called Network Interface Card (NIC), can only connect to a network.

Question 2.
Define Computer Networks?
Answer:
Two or more computers connected through a communication media that allows exchange of information between computers is called a Computer Network.
eg: LAN, MAN, WAN

Question 3.
Do you heard about work station/Node. What is it?
Answer:
A personal computer connected to a network is called work station/Node.

Question 4.
Define a protocol.
Answer:
A protocol is the collection of rules and conventions used to exchange information between computers as a network.

Question 5.
Is the following a valid IP address? 258.1001.10.1. Justify your answer?
Answer:
No. It is not a valid IP address. An IP address has 4 parts numeric address. Each parts contains 8 bits. By using 8 bits we can represent a decimal number between 0 to 255. Here 258 and 1001 are greater than 255. So it is not valid.

Question 6.
Mr. Dixon purchased a Laptop with bluetooth technology. What is bluetooth?
Answer:
It is a specification that allows mobile phones, computers and PDAS to be connected wirelessly over short distance.

Question 7.
Some Airport or college campus offers Wi-Fi facility. What is Wi-Fi?
Answer:
Wi-Fi means Wireless Fidelity. It is a wireless technology. Some organisation offers Wi-Fi facility. Here we can connect internet wirelessly over short distance, using Wi-Fi enabled devices.

Question 8.
What is a protocol?
Answer:
A protocol is a collection of rules and regulations to transmit data from one computer to another on a network.
eg: Http, FTP, TCP/IP, etc.

Question 9.
Explain Infrared waves in detail?
Answer:
These waves are used for transmitting data in short distance and its frequency range is 300 GHz to 400 GHz. Tv’s remote control, wireless mouse and intrusion detectors etc are the devices that used infrared.

Question 10.
Define resource sharing.
Answer:
Resource sharing means the computers on a network can share resources like software (programs, data) and hardware (printer, scanner, CD drive etc.).

Question 11.
Name two classification of communication channels between computers in a network.
Answer:
The two classification of communication channels are guided media and unguided media.

Question 12.
What is the use of a Repeater ?
Answer:
A Repeater is a device used to strengthen weak signals on the network and retransmits them to the destination.

Question 13.
Differentiate between router and Bridge.
Answer:
Bridge is a device used to link same type of networks while Router is similar to a bridge, but it can connect two networks with different protocols.

Question 14.
Categorise and classify the different types of network given below.
ATM network, Cable television network, Network within the school, Network at home using Bluetooth, Telephone network, Railway network ,
Answer:

• PAN: Network at home using Bluetooth
• LAN: Network within the school
• MAN: Cable television network
• WAN: ATM network, Telephone network, Railway network

Question 15.
What is PAN?
Answer:
PAN means Personal Area Network. It is used to connect devices situated in a small radius by using guided media(USB cable)or unguided media (Bluetooth, infrared,etc).

Plus One Computer Networks Three Mark Questions and Answers

Question 1.
What are the advantages of Networks?

OR

In a school lab all the 10 computers are connected to a network. We know that there is no need of 10 printers or 10 scanners why? Explain the advantages of Networks?
Answer:
The advantages of Networks are given below:
1. Resource sharing:
All the computers in a network can share software (programs, data) and hardware (printer, scanner, CD drive etc.).

2. Reliability:
If one computer fails, the other computer can perform the work without any delay. This is very important for banking air traffic control and other application.

3. Price Vs Performance:
A main frame computer can be 10 times faster than a PC but it costs thousand times a PC. Therefore instead of a main frame 10 personal computers are used with less cost and same performance.

4. Communication Medium:
It is a powerful communication medium. We can exchange information between computers in a network.

5. Scalable:
This means, System performance can be increased by adding computers to a network.

Question 2.
Match the following,

(1) Protocol	a. edu
(2) Top level Domain	b. Microwave Tower
(3) Communication Medium	c. HTTP
(4) Network	d. Mesh
(5) Topology	e. in
(6) Geographical Top level domain	f. WAN

Answer:
(1) c
(2) a
(3) b
(4) f
(5) d
(6) e

Question 3.
Your friend told you that a workstation and server are same. What is your opinion? Is it true?
Answer:
No it is not true. A work station is a ordinary computer connected to a network. But a server is a powerful computer connected to a network. Its main aim is to serve the needs of a workstation. Server is the master and workstations are the slaves.

Question 4.
Your friend told you that there are different types of servers. Do you agree with that ? Justify your answer?
Answer:
Yes, there are different types of servers, dedicated and non dedicated servers.
1. Dedicated Server:
In large networks, a computer is reserved only for doing server function like sharing software and hardware resources and it is unavailable for running user applications and therefore increases system cost.
eg: File server, Printer server etc.

2. Non dedicated Server:
In smaller networks, a computer is doing the function of a server as well as it also act as a workstation.

Question 5.
Your friend asked you that a Hub or switch is better. What is your opinion?
Answer:
A Hub is a device that receives data from a PC and transmit it to all other PC’s on the network. If two or more PC’s transmit data at the same time, there is a chance for collision.

Hub is a cheap device and data transfer through a Hub is slow. A switch is also a device and it transmits data to the right recipient. Therefore collision rate is low. A switch is faster but it is expensive.

Question 6.
A LAN is classified by their configuration. What are they?
Answer:
They are, peer to peer or client-server.
1. Peer to peer:
In this configuration all the computers have equal priority. That means each computer can function as both a workstation and a server. There is no dedicated server.

2. Client-Server:
In this configuration a computer is powerful which acts as a dedicated server and all others are clients (work stations). Server is the master and others are slaves.

Question 7.
Your friend told you that internet and intranet are same. Do you agree with that. Justify your answer.
Answer:
No. Internet and intranet are not same. They are different.
1. Internet:
It is a network of networks. It means that international network. We can transfer information between computers within nations very cheaply and speedily.
2. Intranet:
A private network inside a company or organisation is called intranet.

Question 8.
Your friend decides to start an internet cafe in his shop. What are the requirements forthis? Help him.
Answer:
The following are the requirements.

1. Computer with a built in Modem or a facility to connect an external modem.
2. A telephone connection
3. An account with an ISP
4. Install respective software
   • eg: Internet explorer or mozilla or netscape Navigator etc.

Question 9.
Consider the following URL and explain each parts.
http://www.nic.kerala.gov.in / results.html.
Answer:
1. http:
http means hyper text transfer protocol. It is a protocol used to transfer hyper text.

2. www:
World Wide Web. With an email address we can open our mail box from anywhere in the world.

3. nic.kerala:
It is a unique name. It is the official website name of National Informatic Centre

4. gov:
It is the top level domain. It means that it is a government organisation’s website,

5. in:
It is the geographical top level domain. It represents the country, in is used for India,

6. results.html:
It represents the file name.

Question 10.
Write any valid email and explain the working of an email.
Answer:
An example of an email id is jobi_cg@rediffmail. com. Here jobi_cg is the user name, rediffmail is the website address and .com is the top level domain which identifies the types of the organisation. To send an email we require an email address.

Some websites provide free email facility. To send an email first type the recipients address and type the message then click the send button. The website’s server first check the email address is valid, if it is valid it will be sent otherwise the message will not be sent and the sender will get an email that it could not deliver the message.

This message will be received by the recipient’s server and will be delivered to recipient’s mail box. He can read it and it will remain in his mail box as ong as he will be deleted.

Question 11.
Is it possible to give numeric address (IP address) to URL instead of string address of a website just like the following, http://210.212.239.70/
Answer:
Our Post Office has two addresses one string ad¬dress (Irinjalakuda) and one numeric code (680121). Just like this the website has also two addresses a string address www.agker.cag.gov.in and a numeric address (http://210.212.239.70/).

Numeric Address (IP address):
It has 4 parts one byte (8 bits) each separated by dots. One byte can represent a number in between 0 to 255. So we can use a number in between 0 to 255 separated by dots. It is the fastest method to access a website. To remember this number is not easy to humans. So a string address is used by humans, eg:- http://203.-127.54.1/

String Address:
It uses a string to represent a website, it is familiar to the humans. The string address is mapped back to the numeric address using a Domain Name System (DNS). It may consists of 3 or 4 parts. The first part is www., the second part is website name, the third top level domain and the fourth geographical top level domain,
eg: www.kerala.gov.in

Question 12.
Arun is in charge of networking the computers in your newly built computer lab.

1. Suggest any two options for communication media that can be usedfor connecting computers in your school lab.
2. Explain the structure and features of both. (3)

Answer:
1. Twisted pair cables and coaxial cables.

2. Twisted Pair Wire :
Two copper wires individually insulated, twisted around each other and covered by a PVC. There are two types of twisted pair wire. They are UTP and STP. It is very cheap and easy to install.

Coaxial Cable:
A sturdy copper wire(conductor) is insulated by plastic. This is covered just like a mesh by a conductor , which in turn is enclosed in an protective plastic coating. Compared to twisted pair wire it is more expensive, less flexible and more difficult to install. But it is more reliable and carry for higher data rates.

Question 13.
The computer uses digital signals and this signal is transmitted through telephone lines to computers at distant locations. Discuss how this is made possible.
Answer:
1. Modem

2. A Modem is a two in one device. That is it performs two functions. It is used to convert Digital signals to Analog, the process is Modulation(DAM) and the reverse process is converting Analog to Digital known as Demodulation (ADD).

Question 14.
Explain the structure of the television cable in your house.
Answer:
Coaxial Cable:
A sturdy copper wire(conductor) is insulated by plastic. This is covered just like a mesh by a conductor, which in turn is enclosed in an protective plastic coating. Compared to twisted pair wire it is more expensive, less flexible and more difficult to install. But it is more reliable and carry far higher data rates. The various coaxial cables are RG – 8, RG – 9, RG – 11,…………

Question 15.
Answer the following questions from the list given below.
[Router, Modem, Bridge, Gateway]
Answer:

1. Device used to connect a network using TCP/IP protocol and a network using IPX/SPX protocol.
2. Device that can convert a message from one code to another and transfer from one network to a network of another type.
3. Device used to link two networks of the same type.

Question 16.
Find the most suitable match.

A	B
i. Web site	1. file with extension .htm
ii. Home page	2. www.yahoo.com
iii. Web page	3. first page of a web site
iv. Portal	4. www.keralapsc.org.

Answer:
i. www.keralapsc.org
ii. first page of a web site
iii. file with extension.htm
iv. www.yahoo.com

Question 17.
What do you mean by line of sight method of propagation.

OR

Why Microwave station use tall towers instead of short one?
Answer:
MicroWave signals can travel only in straight line. It cannot bend when the obstacles in between. There fore it uses tall towers instead of short one. The dish like antenna mounted on the top of the tower. Hence the two antennas must be in a straight line, able to look at each other without any obstacle in between.

Question 18.
Mr. Alvis took a photograph by using his mobile phone and he sends that photograph to his friend by using blue tooth. What is Bluetooth? Explain.
Answer:
This technology uses radio waves in the frequency range of 2.402 GHz to 2.480 GHz. And transmit data in short distance. Mobile phones, Laptops, tablets etc use Bluetooth technology to transmit data.

By using Bluetooth Dongle(a small device that can be buy from the shop) we can convert non Bluetooth PC into Bluetooth enabled and transmits data with data transmission rate of 3 Mbs onwards.

Question 19.
Differentiate Wi-Fi and Wi-Max in detail.
Answer:
WI Fi(Wireless Fidelity) uses radio waves to transmit information across a network in a range 2.4 GHz to 5 GHz in short distance. Nowadays this technology is used to access internet in Laptops, Desktops, Tablets, Mobile phones etc. But Wi MAX(Wireless Microwave Access) uses microwaves to transmit information across a network in a range 2 GHz to 11 GHz over very long distance.

Question 20.
What is MAC address? What is the difference between a MAC address and an IP address?
Answer:
MAC means Media Access Control address. It is a unique 12 digit hexadecimal number(IMEI for mobile phones, it is a 15 digit decimal number) assigned to each NIC by its manufacturer. This address is known as MAC address and it is permanent. It is of the form. MM:MM:MM:SS:SS:SS.

The first MM:MM:MM contains the ID number of the adapter company and the second SS:SS:SS represents the serial number assigned to the adapter by the company.

IP address means Internet Protocol address. It has 4 parts numeric address. Each parts contains 8 bits. By using 8 bits we can represent a decimal number between 0 to 255(28=256 numbers). Each part is separated by dot. A total of 4 × 8=32 bits used. But nowadays 128 bits are used for IP address.

Question 21.
What is the limitation of microwave transmission? How is it eliminated?
Answer:
MicroWave signals can travel only in straight line. It cannot bend when the obstacles in between. Therefore it uses tall towers instead of short one. The dish like antenna mounted on the top of the tower. Hence the two antennas must be in a straight line, able to look at each other without any obstacle in between.

Question 22.
Explain the different types of networks.
Answer:
The networks are classified into the following.
1. Local Area Network (LAN):
This is used to connect computers in a single room, rooms within a building or buildings of one location by usin(j twisted pair wire or coaxial cable. Here the computers can share Hardware and software. Data transferrate is high and error rate is less,
eg: The computers connected in a school lab.

2. Metropolitan Area Network (MAN):
A Metropolitan Area Network is a network spread over a city. For example a Cable TV network. MAN have lesser speed than LAN and the error rate is less. Here opticalfibre cable is used.

3. Wide Area Network (WAN):
This is used to connect computers over a large geographical area. It is a network of networks. Here the computers are connected using telephone lines or Micro Wave station or Satellites. Internet is an example for this. LAN and MAN are owned by a single organisation but WAN is owned by multiple organisation. The error rate in data transmission is high.

Question 23.

1. To make data transfer faster, a switch stores two different addresses of all the devices connected to it. What are they?
2. There are 5 computers in your computer lab. Write short notes on any three possible methods to interconnect these computers. Draw the diagram of each method.

Answer:
1. Identification of computers over a network:
A computer gets a data packet on a network, it can identify the senders address easily. It is similarto oursnails mail, each letter is stamped in sender’s post office as well as receiver’s post office.

(1) Media Access Control(MAC) address:
It is a unique 12 digit hexadecimal number(IMEI for mobile phones, it is a 15 digit decimal number) assigned to each NIC by its manufacturer. This address is known as MAC address and its permanent. It is of the form. MM:MM:MM:SS:SS:SS. The first MM:MM:MM contains the ID number of the adapter company and the second SS:SS:SS represents the serial number assigned to the adapter by the company.

(2) Internet Protocol (IP) address:
An IP address has 4 parts numeric address. Each parts contains 8 bits. By using 8 bits we can represent a decimal number between 0 to 255(2°=256 numbers). Each part is separated by dot. A total of 4*8=32 bits used. But nowadays 128 bits are used for IP address.

2. Network topologies:
Physical or logical arrangement of computers on a network is called structure or topology. It is the geometrical arrangement of computers in a network. The major topologies developed are star, bus, ring, tree and mesh.

(1) Star Topology:
A star topology has a server all other computers are connected to it. If computer A wants to transmit a message to computer B. Then computer A first transmit the message to the server then the server retransmits the message to the computer B.

That means all the messages are transmitted through the server. Advantages are add or remove workstations to a star network is easy and the failure of a workstation will not effect the other. The disadvantage is that if the server fails the entire network will fail.

(2) Bus Topology:
Here all the computers are attached to a single cable called bus. Here one computer transmits all other computers listen. Therefore it is called broadcast bus. The transmission from any station will travel in both the direction. The connected computers can hear the message and check whether it is for them or not.

Advantages are add or remove computer is very easy. It requires less cable length and the installation cost is less. Disadvantage is fault detection is very difficult because of no central computer.

(3) Ring Topology:
Here all the computers are connected in the shape of a ring and it is a closed loop. Here also there is no central computer. Here a computer transmits a message, which is tagged along with its destination computer’s address.

The message travels in one direction and each node check whether the message is for them. If not, it passes to the next node. It requires only short cable length. If a single node fails, at least a portion of the network will fail. To add a node is very difficult.

(4) Hybrid Topology:
It is a combination of any two or more network topologies. Tree topology and mesh topology can be considered as hybrid topology.
(a) Tree Topology:
The structure of a tree topology is the shape of an inverted tree with a central node and branches as nodes. It is a variation of bus topology. The data transmission takes place in the way as in bus topology. The disadvantage is that if one node fails, the entire portion will fail.

(b) Mesh Topology:
In this topology each node is connected to more than one node. It is just like a mesh (net). There are multiple paths between computers. If one path fails, we can transmit data through another path.

Question 24.
ABC Ltd. required to connect their computers in their company without using wires. Suggest suitable medium to connect the computers. Explain. (3)
Answer:
Unguided Media

1. Radio waves: It transmits data at different frequencies ranging from 3 kHz. to 300 GHz.
2. Microwaves: Microwave signals can travel in straight line if there is any obstacle in its path, it can’t bend. So it uses tall towers instead of short one.
3. Infrared waves: These waves are used for transmitting data in short distance and its frequency range is 300 GHz to 400 GHz.

Question 25.
It is needed to set up a PAN, interconnecting one tablet, two mobile phones and one laptop. Suggest a suitable communication technology and list its features for the following situations:

1. the devices are in a room at distance of 5 to 10 meters.
2. the devices are in different rooms at a distance of 25 to 50 meters.

Answer:
1. Wireless communication technologies using radio waves
Bluetooth:
This technology uses radio waves in the frequency range of 2.402 GHz to 2.480 GHz. And transmit data in short distance. Mobile phones, Laptops, tablets etc use Bluetooth technology to transmit data.

2. Wi Fi(Wireless Fidelity):
It uses radio waves to transmit information across a network in a range 2.4 GHz to 5 GHz in short distance. Nowadays this technology is used to access internet in Laptops, Desktops, tablets. Mobile phones etc.

Question 26.
Computers and other communication devices can be connected a network using wireless technology.

1. A song is transferred from mobile phone to a laptop using this technology. Name the transmission medium used here.
2. Explain any other three communication media which use this technology

Answer:

1. Blue tooth or Radio waves
2. Wireless communication technologies using radio waves

(1) Bluetooth:
This technology uses radio waves in the frequency range of 2.402 GHz to 2.480 GHz. And transmit data in short distance. Mobile phones, Laptops, tablets etc use Bluetooth technology to transmit data.

(2) Wi Fi(Wireless Fidelity):
It uses radio waves to transmit information across a network in a range 2.4 GHz to 5 GHz in short distance. Nowadays this technology is used to access internet in Laptops, Desktops, tablets, Mobile phones etc.

(3) Wi MAX(Wireless Microwave Access):
It uses micro waves to transmit information across a network in a range 2 GHz to 11 GHz over very long distance.

(4) Satellites:
By using satellite we can communicate from any part of the world to any other. The ground stations are connected via the satellite. The data signals transmitted from earth to satellite (uplink) and from the satellite to the earth (downlink).

Question 27.
Find the correct match for each item in column A from columns B and C.

A	B	C
(a) QR code	(i) Secondary memory	1. Reduces the amount of traffic on a network
(b) USB flash drives	(ii) Internet connectivity	2. Dish antenna is required
(c) Bridge	(iii) Bar code reader	3. Two dimensional way of storing data
(d) FTTH	(vi) Mobile service	4. Uses EEPROM chip for data storage
	(v) Network device	5. Transmits data packets to all devices
		Uses optical fibre for data tranmission

Answer:
(a) QR code – (iii) – 3
(b) USB flash drives – (i) – 4
(c) Bridge – (V) – 1
(d) FTTH – (ii) – 6

Question 28.
Write notes on the following:

1. IP address
2. MAC address
3. Modem

Answer:
1. IP address:
An IP address has 4 parts numeric address. Each parts contains 8 bits. By using 8 bits we can represent a decimal number between 0 to 255(2⁸=256 numbers). Each part is separated by dot. A total of 4 × 8=32 bits used. But nowadays 128 bits are used for IP address.

2. Media Access Control(MAC) address:
It is a unique 12 digit hexadecimal number(IMEI for mobile phones, it is a 15 digit decimal number) assigned to each NIC by its manufacturer. This address is known as MAC address. It is of the form. MM:MM:MM:SS:SS:SS.

3. Modem:
It is a device used to connect the computer to the internet. It converts digital signal into analog signal (modulation) and vice versa (De modulation)

Question 29.
Compare any three types of networks based on span of geographical area.
Answer:
Types of networks:
The networks are classified into the following based upon the amount of geographical area that covers.
1. Personal Area Ne,twork(PAN):
It is used to connect devices situated in a small radius by using guided media or unguided media

2. Local Area Network (LAN):
This is used to connect computers in a single room, rooms within a building or buildings of one location by using twisted pair wire or coaxial cable. Here the computers can share Hardware and software. Data transfer rate is high and error rate is less,
eg:The computers connected in a school lab.

3. Metropolitan Area Network (MAN):
A Metropolitan Area Network is a network spread over a city. For example a Cable TV network. MAN have lesser speed than LAN and the error rate is less. Here optical fiber cable is used.

4. Wide Area Network (WAN):
This is used to connect computers over a large geographical area. It is a network of networks. Here the computers are connected using telephone lines or Micro Wave station or Satellites.

Internet is an example for this. LAN and MAN are owned by a single organization but WAN is owned by multiple organization. The error rate in data transmission is high.
In short

Plus One Computer Networks Five Mark Questions and Answers

Question 1.
Explain the different network topologies.
Answer:
physical or logical arrangement of computers of a network is called structure or topology. It is the geometrical arrangement of computers in a network. The major topologies developed are star, bus, ring, tree and mesh.
1. Star Topology:
A star topology has a server all other computers are connected to it. If computer A wants to transmit a message to computer B. Then computer A first transmits the message to the server then the server retransmits the message to the computer B.

That means all the messages are transmitted through the server. Advantages are add or remove workstations to a star network is easy and the failure of a workstation will not effect the other. The disadvantage is that if the server fails the entire network will fail.

2. Bus Topology:
Here all the computers are attached to a single cable called bus. Here one computer transmits all other computers listen. Therefore it is called broadcast bus. The transmission from any station will travel in both the direction. The connected computers can hear the message and check whether it is for them or not.

Advantages are add or remove computer is very easy. It requires less cable length and the installation cost is less. Disadvantage is fault detection is very difficult because of no central computer.

3. Ring Topology:
Here all the computers are connected in the shape of a ring and it is a closed loop. Here also there is no central computer. Here a computer transmits a message, which is tagged along with its destination computer’s address.

The message travels in one direction and each node check whether the message is for them. IF not, it passes to the next node. It require only short cable length. If a single node fails, atleast a portion of the network will fail. To add a node is very difficult.

4. Hybrid Topology:
It is a combination of any two or more network topologies. Tree topology and mesh topology can be considered as hybrid topology.

(a) Tree Topology:
The structure of a tree topol-ogy is the shape of an inverted tree with a central node and branches as nodes. It is a variation of bus topology. The data transmis-sion takes place in the way as in bus topology. The disadvantage is that if one node fails, the entire portion will fail.

(b) Mesh Topology:
In this topology each node is connected to more than one node. It is just like a mesh (net). There are multiple paths between computers. If one path fails, we can transmit data through another path.

Question 2.
What are the different data communication equipments?
Answer:
1. Modem:
A Modem is a two in one device. That is it performs two functions. It is used to convert Digital signals to Analog, the process is Modulation (DAM) and the reverse process is converting Analog to Digital known as Demodulation (ADD).

2. Multiplexer(Many to One):
A multiplexer is a device that combines the inputs from different sources and produces one output. A demultiplexer does the reverse process.

3. Bridge:
It is a device used to link two same type of networks.

4. Router:
It is a device used to link two networks with different protocols.

5. Gateway:
It is a device used to link two networks of different types.lt can convert a message from one code to another.

Question 3.
Explain the protocol TCP/IP.
Answer:
1. TCP:
(Transmission Control Protocol) is a connection oriented protocol. It is responsible for sending the data from one PC to another and also verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP adds support to detect errors or lost data and to trigger retransmission until the data is correctly and completely received.

2. IP:
is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address (the IP number). The Internet authorities assign ranges of numbers to different organizations.

The organizations assign groups of their numbers to departments. IP operates on gateway machines that move data from department to organization to region and then around the world. In short TCP handle the flow control and error free packet delivery and IP provides basic addressing and data packets forwarding services.
eg: 101.65.105.255

Question 4.
What is a protocol. Explain any four.

OR

Why protocol is necessary for communication? Explain any two of them.
Answer:
A protocol is a collection of rules and regulations to transfer data from one location to another. Transmission Control Protocol (TCP), which uses a set of rules to exchange messages with other Internet points at the information packet level. Internet Protocol (IP), which uses a set of rules to send and receive messages at the Internet address level.
1. FTP:
File Transfer Protocol which is used for transferring files between computers connected to local network or internet.

2. HTTP:
HTTP is a protocol used for WWW for enabling the web browse to access web server and request HTML documents.