Health

1. CHAPTER TWO
1
Networking
and
Internet

2. Content
 Computer Network overview
 Types of Network
 Internet Basics
• web
• Tools and sevices the internet
• browsers
• email
• purpose of the internet
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3. 2.1 Computer Network
 Computer network is a
that allows
people to share information.
Advantages of a computer network system
are:
sharing
sharing
−Distribution of
−Sharing of 3

4. What is a Network?
in which a
• A computer network refers to the system
of two or more interconnected computers
by a media that allows them to share
• Sharing is the purpose of computer
networking.
• The ability to share information 4

5. Why Computer Networks are
needed?
• With the availability and power of today's personal
computers, you might ask why networks are needed.
• Networks increase efficiency and reduce costs.
• Sharing information (or data)
• Sharing hardware and software
• Centralizing administration and support 5

6. Network components and functions
 Servers—Computers that provide shared resources
to network users.
 Clients—Computers that access shared network
resources provided by a server.
 Media—the wires/air that make the connections.
 Resources—any service or device, such as files,
printers, or other items, made available for use by
members of the network.
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7. 2.2 Types of Networks
 Based on the geographical span of coverage,
computer networks are broadly classified
into three major categories:
 Local Area Network (LAN)
 Metropolitan Area Network (MAN)
 Wide Area Network (WAN)
1.Local Area Network
– May be located
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8. …cont’d
2.Metropolitan Area Network
− May span
3.Wide Area Network
− May span a
 Based on network architecture, computer
networks are classified as: peer-to-peer
network and client/server network.
8

9. …cont’d
 Client/Server Network is a network model
designed for the end users called clients, to
access the resources such as songs, films, etc.
from a central computer known as server.
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Figure 4.1: Client/Server Network

10. …cont’d
 Peer-to-Peer network is in which all the
computers are linked together with
for processing
the data.
 Each computer can be a client at one time
and a server at another time.
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Figure 4.2: Peer-To-Peer Network

11. 2.3 Network Topologies
 A network topology is the arrangement with
which computer systems or network devices are
connected to each other.
 Three of the most common topologies are bus,
star and ring.
Bus Topology
 All devices share a single high speed communication
line or cable called a bus.
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Figure 4.3: Bus Topology

12. …cont’d
 Data transmitted by a node is "broadcast" bi-
directionally.
 All nodes receive the signals.
 One of the nodes, recognizing that the signal is
addressed to it, accepts the data and forwards it to the
node attached.
 All signals set bi-directionally are properly terminated at
both ends of the bus.
 Failure of a device does not affect the other devices.
 But failure of the shared communication line can make
all other devices stop functioning.
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13. …cont’d
Star Topology
 All nodes in star topology are connected to a central
device , known as a hub.
 This hub controls all communication between nodes.
 If the hub fails, the entire network communication will
be disabled.
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Figure 4.4: Star Topology

14. …cont’d
Ring Topology
 In ring topology, each node connects to exactly two
other nodes, creating a circular network structure.
 The ring topology uses token ring access method.
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Figure 4.5: Ring Topology

15.  Token ring access method can be described as follows:
−An idle token rotates around the ring
−A sending computer takes the token and attaches the
message to be sent on it.
−The token passes to the neighboring computer and so
forth.
−The receiving computer takes the token and copies
the message and leaves the token to rotate
−The sender again takes the token and removes the
message from the token to make the token empty
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16. 2.4 Internet Basics
 The word Internet is derived from two
words: Interconnection and networks.
 The Internet is a worldwide network of
computer networks connecting millions of
computers around the world.
 The Internet is one of the largest, most
widely used networks (in fact, a network of
networks) that has evolved and grown
overtime.
 The Internet connects millions of computers
globally and provides worldwide
communications to businesses, homes,
schools, and governments.
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17. Advantages of the Internet
The internet helps in various ways:
 To get information
−You can get information about people, products,
organizations, research data, electronic versions of
the printed media, etc. from the Internet.
 To provide information
−Internet is the best and most inexpensive way to let
people know who you are, what you are doing and
have done could be communicated with others.
 Ability to communicate
−It gives people the ability to communicate with other
connected computer users through electronic mail
and real time typed conversations.
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18. 2.5 Internet Applications
Internet services include but not limited to:
 World Wide Web(WWW)
 Electronic Mail
 File Transfer
 Telnet
 Search Services
World Wide Web
− In simpler terms, the Web is an Internet-based
computer network that allows users on one computer
to access information stored on another through the
worldwide network.
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19. Electronic Mail(E-mail)
− Email (Electronic mail) refers to a computer-based
system allowing two or more people to communicate
through the transmission of message by electronic
means.
File Transfer
− Transfer files between computers using File Transfer
Protocol(FTP)
− FTP sites contain books, articles, software, games,
images, sounds, multimedia and more.
Telnet
− Telnet is a program that allows you to log into
computers on the Internet and use online databases,
library catalogs, chat services, and more.
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20. …cont’d
Search Services
− Search engines provide access to a fairly large portion
of the publicly available pages on the Web.
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