Computer Network & Network types | Computer Science for Grade 12 PDF Download

 Page 1


Computer Network
A computer network is a set of nodes like computers and
networking devices that are connected through communication for
the purpose of communication and sharing
resources(hardware/software) among the users.
Networks are used to:
(Benefits of computer network)
• Facilitate communication through email / video conferencing /
instant messaging or any other mode.
• Share hardware devices like a printer or scanner
• Enable file sharing
• Share software or operating programs
• Share information
Disadvantages of computer network
Lack of robustness, security issue, cost of network
Page 2


Computer Network
A computer network is a set of nodes like computers and
networking devices that are connected through communication for
the purpose of communication and sharing
resources(hardware/software) among the users.
Networks are used to:
(Benefits of computer network)
• Facilitate communication through email / video conferencing /
instant messaging or any other mode.
• Share hardware devices like a printer or scanner
• Enable file sharing
• Share software or operating programs
• Share information
Disadvantages of computer network
Lack of robustness, security issue, cost of network
Evolution of 
networking
ARPANET (Advanced Research Projects Agency NETwork): In 1969, The US govt.
formed an agency named ARPANET to connect computers at various universities and
defense agencies. The main objective of ARPANET was to develop a network that could
continue to function efficiently even in the event of a nuclear attack.
The National Science Foundation Network (NSFNET) was a program of coordinated,
evolving projects sponsored by the National Science Foundation (NSF) from 1985 to
1995 to promote advanced research and education networking in the United States
Internet (INTERconnection NETwork): The Internet is a worldwide network of
computer networks. It is not owned by anybody. The internet has evolved from
ARPANET. The internet is a globally connected network system that utilizes TCP/IP to
transmit information. following services are instantly available through internet :
Email, Web-enabled audio/video conferencing services, Online movies and gaming ,
Data transfer/file-sharing, Instant messaging , Internet forums , Social networking ,
Online shopping ,Financial services
Interspace: is a client/server software program that allows multiple users to
communicate online with real –time audio, video and text chat in dynamic 3D
environments.
Page 3


Computer Network
A computer network is a set of nodes like computers and
networking devices that are connected through communication for
the purpose of communication and sharing
resources(hardware/software) among the users.
Networks are used to:
(Benefits of computer network)
• Facilitate communication through email / video conferencing /
instant messaging or any other mode.
• Share hardware devices like a printer or scanner
• Enable file sharing
• Share software or operating programs
• Share information
Disadvantages of computer network
Lack of robustness, security issue, cost of network
Evolution of 
networking
ARPANET (Advanced Research Projects Agency NETwork): In 1969, The US govt.
formed an agency named ARPANET to connect computers at various universities and
defense agencies. The main objective of ARPANET was to develop a network that could
continue to function efficiently even in the event of a nuclear attack.
The National Science Foundation Network (NSFNET) was a program of coordinated,
evolving projects sponsored by the National Science Foundation (NSF) from 1985 to
1995 to promote advanced research and education networking in the United States
Internet (INTERconnection NETwork): The Internet is a worldwide network of
computer networks. It is not owned by anybody. The internet has evolved from
ARPANET. The internet is a globally connected network system that utilizes TCP/IP to
transmit information. following services are instantly available through internet :
Email, Web-enabled audio/video conferencing services, Online movies and gaming ,
Data transfer/file-sharing, Instant messaging , Internet forums , Social networking ,
Online shopping ,Financial services
Interspace: is a client/server software program that allows multiple users to
communicate online with real –time audio, video and text chat in dynamic 3D
environments.
Data Communication 
Terminologies
Communication means means of sending or receiving information,
such as phone lines or computers.
Components of communications sender, receiver, message,
communication media, protocols
Page 4


Computer Network
A computer network is a set of nodes like computers and
networking devices that are connected through communication for
the purpose of communication and sharing
resources(hardware/software) among the users.
Networks are used to:
(Benefits of computer network)
• Facilitate communication through email / video conferencing /
instant messaging or any other mode.
• Share hardware devices like a printer or scanner
• Enable file sharing
• Share software or operating programs
• Share information
Disadvantages of computer network
Lack of robustness, security issue, cost of network
Evolution of 
networking
ARPANET (Advanced Research Projects Agency NETwork): In 1969, The US govt.
formed an agency named ARPANET to connect computers at various universities and
defense agencies. The main objective of ARPANET was to develop a network that could
continue to function efficiently even in the event of a nuclear attack.
The National Science Foundation Network (NSFNET) was a program of coordinated,
evolving projects sponsored by the National Science Foundation (NSF) from 1985 to
1995 to promote advanced research and education networking in the United States
Internet (INTERconnection NETwork): The Internet is a worldwide network of
computer networks. It is not owned by anybody. The internet has evolved from
ARPANET. The internet is a globally connected network system that utilizes TCP/IP to
transmit information. following services are instantly available through internet :
Email, Web-enabled audio/video conferencing services, Online movies and gaming ,
Data transfer/file-sharing, Instant messaging , Internet forums , Social networking ,
Online shopping ,Financial services
Interspace: is a client/server software program that allows multiple users to
communicate online with real –time audio, video and text chat in dynamic 3D
environments.
Data Communication 
Terminologies
Communication means means of sending or receiving information,
such as phone lines or computers.
Components of communications sender, receiver, message,
communication media, protocols
Switching techniques
Switching Techniques: Switching techniques are used for
transmitting data across networks. Different ways of sending data
across the network are:
Circuit Switching:
• First the complete end-to-end
transmission path is established
between the source and the
destination computers.
• Then the message is transmitted
through the path.
• The main advantage of
thistechnique is guaranteed
delivery of the message.
• Mostly used for voice
communication.
Page 5


Computer Network
A computer network is a set of nodes like computers and
networking devices that are connected through communication for
the purpose of communication and sharing
resources(hardware/software) among the users.
Networks are used to:
(Benefits of computer network)
• Facilitate communication through email / video conferencing /
instant messaging or any other mode.
• Share hardware devices like a printer or scanner
• Enable file sharing
• Share software or operating programs
• Share information
Disadvantages of computer network
Lack of robustness, security issue, cost of network
Evolution of 
networking
ARPANET (Advanced Research Projects Agency NETwork): In 1969, The US govt.
formed an agency named ARPANET to connect computers at various universities and
defense agencies. The main objective of ARPANET was to develop a network that could
continue to function efficiently even in the event of a nuclear attack.
The National Science Foundation Network (NSFNET) was a program of coordinated,
evolving projects sponsored by the National Science Foundation (NSF) from 1985 to
1995 to promote advanced research and education networking in the United States
Internet (INTERconnection NETwork): The Internet is a worldwide network of
computer networks. It is not owned by anybody. The internet has evolved from
ARPANET. The internet is a globally connected network system that utilizes TCP/IP to
transmit information. following services are instantly available through internet :
Email, Web-enabled audio/video conferencing services, Online movies and gaming ,
Data transfer/file-sharing, Instant messaging , Internet forums , Social networking ,
Online shopping ,Financial services
Interspace: is a client/server software program that allows multiple users to
communicate online with real –time audio, video and text chat in dynamic 3D
environments.
Data Communication 
Terminologies
Communication means means of sending or receiving information,
such as phone lines or computers.
Components of communications sender, receiver, message,
communication media, protocols
Switching techniques
Switching Techniques: Switching techniques are used for
transmitting data across networks. Different ways of sending data
across the network are:
Circuit Switching:
• First the complete end-to-end
transmission path is established
between the source and the
destination computers.
• Then the message is transmitted
through the path.
• The main advantage of
thistechnique is guaranteed
delivery of the message.
• Mostly used for voice
communication.
Switching techniques
Packet Switching:
• Using the TCP protocol a single large message is
divided into a sequence of packets of size limits
from 128 to 4096 bytes.
• Each packet is independent and has the address of
sender and destination.
• The IP (Internet protocol) does the routing for the
packets. It keeps track of all the different routes
available to the destination. If one route is not
available it finds the alternate route to the
destination.
• At the destination, the TCP protocol re-assembles
the packets into the complete message.
• If any packets are lost or damaged, a request is
sent to retransmit the same message.