2. A computer network is a collection
of interconnected computers and
other
devices which are able to communicate
with each other and share hardware
and software resources.
The term interconnected means
that there exists a path through
which data can be transmitted from
one computer / device to another.

3. • Information Sharing
• Hardware Sharing
•Software Sharing
•Time efficient
• Cost saving

4. LAN WAN
MAN
PAN

5. Network of Communicating devices (Computer, Phone, MP3/MP4
Player, Camera etc.) in the proximity of an individual.
Covers an area of a few meters radius.
Can be set up using guided media (USB cable) or unguided media
(Bluetooth, Infrared).

6. Network of computing/Communicating devices in
A room,
A building, or
A campus.
Covers an area of a few meters to a few kilometres radius.
Usually contains a single LAN, or sometimes one building can contain a few
small LANs (Like some schools have independent LANs in each computer lab.).
Can be set up using guided media or unguided media.
If a LAN is setup using unguided media, it is known as WLAN (wireless LAN).

7. Network of computing/communicating devices within a city.
Covers an area of a few kilometres to a few hundred kilometres radius.
A network of schools, or banks, or Government offices etc., within a city, are
examples of MANs.
All types of communication media (guided and unguided) are used to set up a
MAN.
Typically owned and operated by a single entity such as a government body or
a large corporation.

8. Network of computing/communicating devices crossing the limits of a city,
country, or continent.
Covers an area of over hundreds of kilometre radius.
A network of ATMs, BANKs, National Government Offices, International
Organizations' Offices etc., spread over a country, continent, or covering many
continents are examples of WANs.
All types of communication media (guided and unguided) are used to set up a
WAN.
The best known example of a WAN is the internet.

10. GUIDED
(Wired)
UNGUIDED
(Wireless)
Twisted
Pair
Cable
Co-axial
Cable
Optical
Fiber
Cable
Radio
Waves
Micro
Waves
Infrared
Waves

18. A Topology is an arrangement of physical connections
among nodes in a network.
A Node is a device, which is directly connected to a
computer network. It can be a computer or any other
device like printer, scanner etc.

19. In bus topology all the nodes are connected to a main cable called
backbone. If any node has to send some information to any other node, it
sends the signal to the backbone.
A small device called terminator is attached at each end of the backbone.
When the signal reaches the end of backbone, it is absorbed by the
terminator and the backbone gets free to carry another signal.

20. In star topology each node is directly connected to a hub/switch. If any
node has to send some information to any other node, it sends the signal to
the hub/switch. In the case of a switch the signal is sent only to the intended
node(s). Star topology generally requires more cable than bus topology.

21. Tree topology is a combination of bus and star topologies. It is used to
combine multiple star topology networks. All the stars are connected
together like a bus. This bus-star hybrid approach supports future
expandability of the network

22. A ring network is a network topology in which each node
connects to exactly two other nodes, forming a single
continuous pathway for signals through each node - a
ring. Data travels from node to node, with each node
along the way handling every packet..

23. A network protocol is a set of rules for communication among
networked devices.
Protocols generally includes rules of how and when a device can
send or receive the data, how is the sent data packaged, and how it
reaches its destination.
There are a number of protocols defined for computer networks.
Some of them are :
• File transfer protocol (FTP) – used to transmit files.
• Simple mail transfer protocol (SMTP) – used to transmit e-
mail messages.
• Post office protocol (POP) – allows the recipient to retrieve
messages.
• Wireless application protocol – enables wireless devices to
access and use the Internet using a client/server network.

24. Other than the transmission media many other devices are required to form
computer
networks. Some of these devices are:
• NIC : Network Interface Card is a device that enables a computer to connect to a
network and communicate.
• Hub : A Hub is an electronic device that connects several nodes to form a network
and
redirects the received information to all the connected nodes in broadcast mode.

25. • Switch : A Switch is an intelligent device that connects several nodes to form a
network and redirects the received information only to the intended node(s).
• Repeater : A Repeater is a device that is used to regenerate a signal which is on its
way
through a communication channel. A repeater regenerates the received signal
and re-transmits it to its destination.
• Gateway : A Gateway is a device, which is used to connect different types of
networks and perform the necessary translation so that the connected networks can
communicate properly.