Transcript Computer networks - Kendriya Vidyalaya

Computer networks
SATISH MISHRA,PGT CS ,KV TRIMULGHERRY
What is a computer Network?
 A network is any collection of independent
computers that communicate with one another over
a shared network medium. A computer network is a
collection of two or more connected computers.
Every network includes:
 At least two computers Server or Client workstation.
 Networking Interface Card's (NIC)
 A connection medium, usually a wire or cable,
although wireless communication between
networked computers and peripherals is also
possible.
 Network Operating system software, such as
Microsoft Windows NT or 2000, Novell NetWare, Unix
and Linux.
Types of Networks:
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LANs (Local Area Networks)
WANs (Wide Area Networks)
Internet
Intranet
MANs (Metropolitan area Networks)
LANs (Local Area Networks)
 A network is any collection of independent computers that
communicate with one another over a shared network
medium. LANs are networks usually confined to a
geographic area, such as a single building or a college
campus. LANs can be small, linking as few as three
computers, but often link hundreds of computers used by
thousands of people. The development of standard
networking protocols and media has resulted in worldwide
proliferation of LANs throughout business and educational
organizations.
WANs (Wide Area Networks)
 Wide area networking combines multiple LANs that are
geographically separate. This is accomplished by
connecting the different LANs using services such as
dedicated leased phone lines, dial-up phone lines (both
synchronous and asynchronous), satellite links, and data
packet carrier services. Wide area networking can be as
simple as a modem and remote access server for
employees to dial into, or it can be as complex as hundreds
of branch offices globally linked using special routing
protocols and filters to minimize the expense of sending
data sent over vast distances.
Internet
 The Internet is a system of linked networks that are worldwide
in scope and facilitate data communication services such as
remote login, file transfer, electronic mail, the World Wide Web
and newsgroups.
With the meteoric rise in demand for connectivity, the Internet
has become a communications highway for millions of users. The
Internet was initially restricted to military and academic
institutions, but now it is a full-fledged conduit for any and all
forms of information and commerce. Internet websites now
provide personal, educational, political and economic resources
to every corner of the planet.
Intranet
 With the advancements made in browser-based
software for the Internet, many private organizations
are implementing intranets. An intranet is a private
network utilizing Internet-type tools, but available
only within that organization. For large organizations,
an intranet provides an easy access mode to
corporate information for employees.
MANs (Metropolitan area Networks)
 The refers to a network of computers with in a City.
Categories of Network:
 Network can be divided in to two main categories:
 Peer-to-peer.
 Server – based.
 In peer-to-peer networking there are no dedicated servers or
hierarchy among the computers. All of the computers are equal and
therefore known as peers. Normally each computer serves as
Client/Server and there is no one assigned to be an administrator
responsible for the entire network.
Peer-to-peer networks are good choices for needs of small
organizations where the users are allocated in the same general
area, security is not an issue and the organization and the network
will have limited growth within the foreseeable future.
The term Client/server refers to the concept of sharing the work
involved in processing data between the client computer and the
most powerful server computer.
Protocols:
 A computer communication protocol is a description
of the rules computers must follow to communicate
with each other.
What is TCP/IP?
 TCP/IP is the communication protocol for
communication between computers on the Internet.
 TCP/IP stands for Transmission Control Protocol
/ Internet Protocol.
 TCP/IP defines how electronic devices (like
computers) should be connected to the Internet, and
how data should be transmitted between them.
 TCP is responsible for breaking data down into IP
packets before they are sent, and for assembling the
packets when they arrive.
 IP is responsible for sending the packets to the
correct destination.
IP Addresses
 Each computer must have an IP address before it can
connect to the Internet.
 Each IP packet must have an address before it can be
sent to another computer.
 This is an IP address: 192.68.20.50
This might be the same IP address: www.google.com
An IP Address Contains 4 Numbers.
 Each computer must have a unique IP address.
 This is your IP address: 180.215.112.16
 TCP/IP uses four numbers to address a computer. The
numbers are always between 0 and 255.
 IP addresses are normally written as four numbers
separated by a period, like this: 192.168.1.50
32 Bits = 4 Bytes
 In computer terms, TCP/IP uses 32 bits addressing.
One byte is 8 bits. TCP/IP uses 4 bytes.
 One byte can contain 256 different values:
 00000000, 00000001, 00000010, 00000011,
00000100, 00000101, 00000110, 00000111, 00001000
.......and all the way up to 11111111.
 Now you know why a TCP/IP address is four numbers
between 0 and 255.
Domain Names
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A name is much easier to remember than a 12 digit number.
Names used for TCP/IP addresses are called domain names.
www.google.com is a domain name.
When you address a web site, like http://www.w3schools.com,
the name is translated to a number by a Domain Name Server
(DNS).
 All over the world, DNS servers are connected to the Internet.
DNS servers are responsible for translating domain names into
TCP/IP addresses.
 When a new domain name is registered together with a TCP/IP
address, DNS servers all over the world are updated with this
information.
Trace your IP
 http://www.tracemyip.org/
Locate 69.63.176.11
 http://www.ip-adress.com/ip_tracer/
HTTP - Hyper Text Transfer Protocol
 HTTP takes care of the communication between a
web server and a web browser.
 HTTP is used for sending requests from a web client
(a browser) to a web server, returning web content
(web pages) from the server back to the client.
HTTPS - Secure HTTP
 HTTPS takes care of secure communication between
a web server and a web browser.
 HTTPS typically handles credit card transactions and
other sensitive data.
SMTP - Simple Mail Transfer Protocol
 SMTP is used for transmission of e-mails.
 The SMTP protocol is used for the transmission of emails. SMTP takes care of sending your email to
another computer.
 Normally your email is sent to an email server (SMTP
server), and then to another server or servers, and
finally to its destination.
POP - Post Office Protocol
 The POP protocol is used by email programs (like
Microsoft Outlook) to retrieve emails from an email
server.
 If your email program uses POP, all your emails are
downloaded to your email program (also called email
client), each time it connects to your email server.
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NIC(NETWORK INTERFACE CARD)
 In computer networking, a NIC provides the hardware
interface between a computer and a network. A NIC
technically is network adapter hardware.
 In new computers, NICs are now pre-installed by the
manufacturer. All NICs feature a speed rating such as
11 Mbps, 54 Mbps or 100 Mbps that suggest the
general performance of the unit.
How does internet works ?
 http://www.youtube.com/watch?v=i5oe63pOhLI&feat
ure=related
Questions ??