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1. Advantages Of Networks
Define Network with examples.
Give importance of Computer
Network.
COMPUTER NETWORK
We can define a Computer Network as a set of two or more connected computers to share
information and other resources (data, files, printers, hard disk, modem, CD-Rom Drive, CD-Writer,
DVD-Rom Drive, DVD-Writer etc.). The computers in a network can share:
Data, Information, Files
Software
Hardware (printers, disk, modems)etc.
EXAMPLES OF COMPUTER NETWORK
o Computer network can be used in an office. Different people in the office can share common
information and printer.
o Net Cafes use Computer Network for internet sharing. Net Cafe Owners can save money by
sharing one DSL Routers / Modem and a single Internet Connection.
o Computer Network is used in Computer Laboratories of Schools, Colleges and other
educational institutes.
o Internet, is also an example of a computer network. Internet is a network of millions of
computers connected through phone lines. People can share information, files and talk with
one another through internet.

2. ADVANTAGES OF COMPUTER
NETWORKS
Following are some important advantages of computer networks:
1. Data and Information Sharing
Different employees of an organization can share common information with the help of computer
network.
2. Software Sharing
Different software can be shared with the help of computer networks.

3. 3. Hardware Sharing
Different hardware can be shared with the help of computer networks. For example, if there are five
computer users in an office, we can save cost by using only one printer with the help of computer
networking. In a computer network, only one computer will manage all printing needs of the
computer users in a small office. In addition, we can share other hard ware devices like hard disks,
CD-Rom Drives / Writers, modems, routers and scanners etc.
4. Money Saving
We can save a lot of money by using computer networking, because of sharing the same software
and hardware in a network.
5. Internet Sharing
We can buy only one DSL internet connection and share it with in whole organization with the help of
computer networking.
6. Easy Communication Within
Organization
We can send and receive messages and files through network. In this way, a file can be moved to
one place to another within an organization without the need of a physical worker to take and carry
the files to a destination. With the help of a command in a computer we can transfer file within
seconds from one room to another.
7. Easy Communication Outside
Organization
We can send and receive emails and share files with other people outside organization using
internet.

4. Types Of Computer Networks
xplain different types of computer
networks:(LAN,WAN,MAN)
Today, we will discuss the main types of computer networks on the basis of
the distance over which they operate. The main types of computer networks
are:
1. LAN - Local-Area Network
2. WAN - Wide-Area Network
3. MAN - Metropolitan-Area Network
1)LAN (Local Area Network)
What is LAN or Local Area
Network
LAN stands for Local Area Network. It covers a small area. Most LANs
are used to connect computers in a single building or group of near
buildings. Hundreds or thousands of computers may be connected through
LAN. LANs are used in office buildings, college or university campus
etc. Local Area Networks can transfer data at a very high speed. Data
transmission speeds of LAN are 1 to 100 megabits per second.
Examples of Local Area Network
Following are examples of LAN:
o LAN is used in a computer lab to connect computers. The students can
share software, files and data in the lab.
o In Internet cafe, many computers can be connected through LAN. These
computers can share single connection of Internet.
o Local Area Network can be used in an office to share common data and a
network printer and any other software or hardware.
o A local area network in a digital library can provide access to
centralized collection of digital books for many readers using
different computers in library building.

5. 2)WAN (Wide Area Network)
What is WAN or Wide Area Network?
WAN stands for wide area network. It covers a large area. WAN
connects computers in different cities, countries and continents. So, Wide
Area Networks are used to transfer data over very long distances across
cities, countries or even in whole world. WANs are used to connect LANs
and other types of networks together, so that users and computers in one
location can communicate with users and computers in other locations.
Computers in WAN are often connected through leased lines telephone
lines. They can also be connected through satellites. Transmission rate of
WAN is 56 kbps to 45 Mbps. WAN is expensive than LAN. WAN is not as fast
as LAN. There is a possibility of error in data transmission due to very
long distance they cover. The largest WAN is the Internet. With the help
of internet, we can send our data in any part of the world.
Examples of WAN
o In air line ticketing system, many offices of an air line company can
be joined together using WAN. A person can get a ticket from any
office in the country.
o A bank with many branches in different cities can connect its branches
through WAN. The customer can use his account from any branch.
3)MAN (Metropolitan-Area Network)
What is MAN or Metropolitan Area
Network?
A metropolitan area network (MAN) is a network that covers an area of the
size of a city. So, a MAN is larger than a local area network but it is
smaller than a WAN. A MAN is optimized for a larger geographical area than
a LAN, ranging from several blocks of buildings to entire cities. MANs can
use communications channels of moderate-to-high data transfer rates. It
may use fiber Optic cable for fast speeds.
A MAN typically includes one or more LANs but cover a small area than WAN.
A MAN often acts as a high-speed network.

6. Examples of MAN or Metropolitan
Area Network:
o Mobile phones systems often use MAN.
o Many local ISPs manage MAN with the help of cable modems within a
city.
o Local cable TV networks also uses MAN technologies.
Differences between LAN and
WAN
The differences between LAN and WAN is as follows:
LAN (Local Area Network)
1. LAN is used to connect computers at one place, in one room
or a building.
2. LAN covers small and limited area.
3. Data transfer speed is very fast in LAN because of small
distance.
4. Local Area network speed is normally form 1 to l00 Mbps.

7. 5. LAN is less costly.
6. LAN is usually connected through wires.
7. Normally, the connection in a LAN is permanent
using wires.
8. LAN is used for sharing data, information, files and
hardware like printers, hard disk, modem etc.
9. LAN has less possibility of data transmission error.
10. LAN is used to transfer data over small distances.
11 LAN is easy to install and configure.
12 LAN is easy to troubleshoot.
WAN (Wide Area Network)
1 WAN is used to connect computers anywhere in the world.
2 WAN can cover larger area. It can cover cities, countries
and even continents.
3 Data transfer speed is slower in WAN.
4 Transmission speeds are normally 56 kbps to 45
Mbps.
5 The hardware needed for a WAN is more expensive.

8. 6 WAN is usually connected through telephone lines, fiber
optic cable or through wireless media.
7 The connection in WAN may not be permanent.
8 WAN is used to share only data and information like Email
and file transfer
9 WAN has more possibility of data transmission error because
of long distance.
10 WAN is used to transfer data over long distances.
11 WAN is difficult to install and configure due to connecting
computers at multiple and distant sites.
12 WANs are difficult to troubleshoot.
Types Of Network Topology
What is a Network Topology?
Network topology is the shape of the network. It is the physical layout of connected devices in a
network. It tells us how a network will look like. The characteristics of a network depend upon the
network topology selected.
Explain different types of network
topologies
Different network topologies are as follows:
1. Bus Topology
2. Ring Topology
3. Star Topology
4. Tree Topology

9. 5. Mesh Topology
1. Bus Topology
Bus topology is the simplest network topology. In bus topology, all computers in network are
connected to a common communication wire. This wire is called BUS. Terminators are used at both
ends of wire.
2. Star Topology
Star Topology is the most popular and widely used network topology in local area networks. In star
topology, all computers are connected with a central device known as HUB or Switch. Now-a-days
Hubs are often replaced by Fast Network Switches. The sender computer sends data to the hub.
The hub sends it to the destination computer. So, all data communication is managed
through HUB or Switch.
Note: The major difference between a Networking Hub and Networking Switch is that HUB
sends data to all computers, and the destination computer will accept it while other computers will
not. On the other hand, Switch sends data only to the destination computer. Therefore, switch can
reduce network traffic and hence provides fast transmission speed.
3. Ring Topology
In Ring topology, each computer is connected to the next computer such that last computer is
connected to the first. Every computer is connected to next computer in the ring. Each computer
retransmits what it receives from the previous computer. Suppose, computer A needs to send data
to computer D. Now the computer A sends data to computer B. As computer B is not the destination
computer, so it will retransmit data to computer C. Finally, Computer C will transfer data to computer
D, the destination computer. When a node sends a message, the message is processed by each
computer in the ring. If a computer is not the destination node, it will pass the message to the next

10. node, until the message arrives at its destination.
4. Tree Topology
Actually, a Tree topology is the combination of two topologies: bus and star topology. A tree
topology combines the characteristics of bus and star topologies. It consists of groups of computer
connected as star topology. These groups are then connected to a central communication medium
(bus cable).
5. Mesh Topology
In a mesh topology, every device on the network is physically connected to every other device on
the network. Therefore, data can be sent on several possible paths from source computer to
destination computer. Mesh topology is more reliable with better performance. It is mostly used in
wide area networks where reliability is important.
Bus Topology Advantages
Disadvantages
Bus Topology
Bus topology is the simplest network topology. In bus topology, all computers in network are
connected to a common communication wire. This wire is called BUS. Terminators are used at both
ends of wire.

11. Advantages of Bus Network Topology
1. It is very simple topology.
2. It is easy to use.
3. It needs small amount of wire for connecting computers.
4. It is less expensive due to small wire needed.
5. If one computer fails, it does not disturb the other computers in network. Other computers will
continue to share information and other resources with other connected computers.
Disadvantages of Bus Network Topology
1. Only small number of computers can be connected in a bus network.
2. Network speed slows down as the number of computer increases in bus topology.
3. Finding a fault is difficult in bus topology.
Advantages and Disadvantages of
Star Topology
Star Topology
Star Topology is the most popular and widely used network topology in local area networks. In star
topology, all computers are connected with a central device known as HUB or Switch. Now-a-days
Hubs are often replaced by Fast Network Switches. The sender computer sends data to the hub.
The hub sends it to the destination computer. So, all data communication is managed through HUB
or Switch.
Note: The major difference between a Networking Hub and Networking Switch is that HUB sends
data to all computers, and the destination computer will accept it while other computers will not. On
the other hand, Switch sends data only to the destination computer. Therefore, switch can reduce
network traffic and hence provides fast transmission speed.

12. Advantages of Star Network
Topology
1. Easy Installation and maintenance
It is easy to maintain network. That is why it is so popular.
2. Adding or removing computers
Adding or removing computers can be done without disturbing the network. We connect the new
computer with the HUB by means of a networking cable. One end of the cable (RJ 45 connector) is
inserted in computer’s Network Interface Card and the other end (RJ 45 connector) is plugged into
the HUB, and that’s it.
3. Fault Diagnosis
In a star network topology, finding faults is easy. If a computer is no more connected with your
network, you can check its cable and connectors or network settings in its Operating system.

13. 4. Network Reliability
Single computer failure will not disturb whole network, since all other computers are connected with
separate links ( wires ) to HUB. Definitely, they will work fine.
5. Better performance
Star topology can prevents the passing of data through an excessive number of nodes. By using a
Switch, at most, 3 devices and 2 links are involved in any communication between any two devices.
6. Device Isolation
Each device is separately connected to HUB or Switch and is isolated. This is why each device
works independently.
Disadvantages of Star Network
Topology
1. In star network topology, data communication depends on HUB. If central hub fails,
then whole network fails.
2. Since each computer will be connected with HUB by means of a separate wire,
star network topology needs more cable to connect computers.
3. It is more expensive due to more wires.
Advantages and Disadvantages of
Ring Network Topology
Ring Topology
In Ring topology, each computer is connected to the next computer such that last computer is
connected to the first. Every computer is connected to next computer in the ring. Each computer
retransmits what it receives from the previous computer. Suppose, computer A needs to send data
to computer D. Now the computer A sends data to computer B. As computer B is not the destination
computer, so it will retransmit data to computer C. Finally, Computer C will transfer data to computer
D, the destination computer. When a node sends a message, the message is processed by each
computer in the ring. If a computer is not the destination node, it will pass the message to the next

14. node, until the message arrives at its destination.
Advantages of Ring Network Topology
1. It is relatively less expensive than a star topology network.
2. In a Ring topology, every computer has an equal access to the network.
3. Performs better than a bus topology under heavy network load
Disadvantages of Ring Network
Topology
1. 1. Failure of one computer in the ring can affect the whole network.
2. It is difficult to find faults in a ring network topology.
3. Adding or removing computers will also affect the whole network since every
computer is connected with previous and next computer.
4. Sending a message from one computer to another takes time according to the
number of nodes between the two computers. Communication delay is directly
proportional to number of nodes in the network.

15. Advantages and Disadvantages of
Tree Topology
Tree Topology
Actually, a Tree topology is the combination of two topologies: bus topology and star topology. A
tree topology combines the characteristics of bus and star topologies. It consists of groups of
computer connected as star topology. These groups are then connected to a central communication
medium (bus cable).

16. Advantages of Tree Network Topology
1. Many software and hardware vendors support tree topology.
2. It provides point-to-point wiring for individual groups.
Disadvantages of Tree Network
Topology
1. If the main backbone line breaks, the entire tree network goes down.
2. It is more difficult to configure and maintain.
3. If any hub fails, related segment will be removed from the network.
Advantages and Disadvantages of
Mesh Topology
Mesh Topology
In a mesh topology, every device on the network is physically connected to every other device on
the network. Therefore, data can be sent on several possible paths from source computer to
destination computer. Mesh topology is more reliable with better performance. It is mostly used in
wide area networks where reliability is important.

17. Advantages of Mesh Network Topology
1. Since, there are many links to transfer data, Mesh topology gets rid of the traffic problem. Data
may be transferred through different links.
2. If one link becomes unusable, it does not disturb the whole system. Other links can be used for
communication.
3. Since each node has physical connection with other nodes, therefore, one node can transfer data
to many nodes at the same time.
Disadvantages of Mesh Network
Topology
1. 1. It is very expensive due to implementation of multiple links for each node.
2. It is difficult to install and reconfigure.
3. Adding or removing a computer is difficult.