Class xI-XII computer networking

1. COMPUTER NETWORKS
Chapter 10
Page 129

2. Contents:
 Computer Networks
 Advantages & Disadvantages
 Components of a network

3. What is a NETWORK?
 The term “Network” means interconnection.
Example: Cable TV, Phone(Land Phone), Human networks.. Etc.
 “Network in any form has always given better results, better
outcomes and better utilization of resources.”

4. Computer Network- An Introduction
 A Computer Network is a collection of interconnected
autonomous computing devices so as to exchange
information and resources.
Eg: connection between your laptop and smart phone
 Autonomous- Independent

5. Advantages of Network
1. Share Resources (Eg-Printer Sharing)
2. Share storage
3. Can share software(Eg-Software can be installed centrally)
4. Improve communication(Eg-Messages can be sent)

6. Disadvantages of networks
1. Complexity
2. If the networks are badly managed,
service can become unusable
3. Server fails, Everything fails
4. Security issues

7. Components of a Computer Network
 (a) Host/Node
 (b) Server
 (c) Client
 (d) Network hardware
 (e) Communication Channel

8. Network Hardware.
 NIC(Network Interface Card)
 Hub,Switch, Router- Connectivity devices

9. Communication Channel
 Hosts in a network interact with other hosts and
server(s) through a communication medium.
 Two types:
 Wired communication medium(Physical Connection eg:
twisted pair cables, OFC etc)
 Wireless communication medium(No physical
Connection eg: radio waves, satellites, infrared waves,
Bluetooth, laser etc)

10. software
 Software of the network make networking possible
 Eg: Protocols, Network Operating System

11. TYPES OF NETWORKS
 A computer network means a group of ‘NETWORKED’computers
 Networks vary in
 Size
 Complexity
 Geographical Spread

12. 1.Types of Network based on
Geographical Spread
 based on Geographical Spread, Networks can be divided into two :
 LAN (Local Area Networks)
 WAN (Wide Area Networks)

13. 1.1 Local Area Network(LAN)
 Small computer networks confined to a localized area.
 The key purpose of a LAN is to serve its users in resource sharing.
 Traditionally, LANs are said to have geographical spread up to 1 km.
 Cables are used to connect the NIC in each computers

14. 1.2 Wide Area Network (WAN)
 The networks spread across countries or a very big geographical area
 Also Called ‘Networks of Networks’
 WAN are often connected through public networks.
 Internet is giant WAN.
 MAN(Metropolitan Area Network)- Which spread over an area as big as a city.

15. PAN- Personal Area Network
 A personal Area Network(PAN) is the
interconnection of information technology
devices with in the range of an individual
person,
 Typically within a range of 10meters.

16. LAN Vs WAN
LAN WAN
1. It spread over a small area It spread over a very large area
2. It is usually costs less to set up It costs higher to set it up
3. It is usually a single network It is usually a network of many networks

17. 2. Types of networks by
Component roles
 On the basis of the role played by network computers in the
network operation, there can be two types of networks:
 Peer to peer networks
 Clent/Server networks

18. 2.1 Peer-to-Peer Network
 Each computers on Peer-to-Peer network is equal
 Each computer can play the role of a client or a server.
 No computer designed as ‘in charge of network operation’
 Computers that serve on a peer-to-peer computer are often termed
as non dedicated servers (Not completely dedicated to the cause of
sharing)
 Suitable for small networks as they are inexpensive and easy to
install.
 They are limited in scope and are difficult to secure.

19. 2.2 Client- Server Networks
 Centralized control.
 Master- Slave networks
 Dedicated server is used.
 Client computer- computing device on the network that
requests and utilizes network resources
 Server-computer on network, dedicated to processing client
requests.

20. 3.Types of Network based on
Communication Channel
 The connections among the hosts are established using specific
communication media.
 Computer networks can be categorized as:
 Wired computer networks
 Wireless computer networks

21. 3.1 Wired computer networks
 Hosts and other devices are connected through
wiring or cables.
 Most commonly used cables in wired networks
are:
 Twisted Pair Cable
 Coaxial Cable(Coax)
 Fiber Optic Cable (Optic Fiber Cable-OFC)

22. 3.2 Wireless computer networks
 The computer networks that use air or environment as the media.
 Data transmitted without requiring any cable or wires, rather by using:
 IR(Infrared)
 RF(Radio frequencies)
 Satellites
 Most commonly used media in wireless
networks are:
 Microwave
 Radio Wave
 Satellite

23. Evolution of Networking
 Evolution of networking started way back in
1969
 ARPANET
 US Dept. of defense

24. ARPANET
 Seeds of today’s internet were planned in 1969
 US Dept of Defence Sponsored Project-ARPANET
 The Goal of the project was to connect computers at different
universities and US Defence
 Advanced Research Projects Agency NETwork
 In mid 1980s another federal agency, the National Science Foundation
created a new, high capacity network called NSFnet (Allowed only
academic research on its network)
 So many private companies built their own networks, which later
interconnected along with ARPANET and NSFnet-that was called Internet

26. The Internet
 The Internet is a vast network that connects computers all over the
world.
 It is an interconnection of large and small networks around the globe
 Through the Internet, people can share information and communicate
from anywhere with an Internet connection.
 Internet is a super-network
 It connects many small networks together and allows all the computers to
exchange information with each other
 All computers on internet have to use a common set of rules for
communication (Called Protocols Eg: TCP/IP)

27. How does Internet Work?
 In internet, most of the computers are not
connected directly to the internet
 Rather they are connected to smaller networks
 Which in turn connected through Gateways to the
internet backbone

28. Let us see how internet functions
1. At source computer, message to be sent is firstly divided into very
small parts called packets
2. Each packet given numbers serial wise
3. All these packets are then sent to the destination
4. The destination computer receives packets in the random order. If a
packet is lost, it is demanded again
5. The packets are reassembled in the order of their number--- Original
Message is obtained

29. Let us see how internet functions

30. Internet Functioning
 All computers on internet have to use a common set of rules for
communication (Called Protocols Eg: TCP/IP)
 TCP (Transmission Control Protocol)
 TCP part is responsible for dividing the file/message into packets on the source
computer, It is also responsible for reassembling the received packet at the
destination computer
 IP (Internet Protocol)
 IP part is responsible for handling the address of destination computer so the
packet is routed(sent) to its proper destination.

31. Interspace
 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 environment
 Most advanced form of communication

32. Switching techniques
 Switched communication networks are those in which data
transferred from source to destination is routed between various
intermediate nodes.
 Switching is the technique by which nodes control or switch data
to transmit it between specific points on a network.
 There are 3 common switching techniques:
 Circuit Switching
 Packet Switching
 Message Switching

33. Circuit Switching
 Circuit switching is the transmission technology that has been used since the
first communication networks in the nineteenth century.
 First the complete physical connection between two computers is
established and then the data are transmitted from the source computer to
the destination.
 When a call is placed the switching equipment within the system seeks out a
physical copper path all the way from the sender to the receiver.
 The circuit is terminated when the connection is closed.
 In circuit switching, resources remain allocated during the full length of a
communication, after a circuit is established and until the circuit is
terminated and the allocated resources are freed.

34. Circuit Switching

35. Message Switching
 In this the source computer sends data or the message to the switching
circuit which stores the data in its buffer.
 Then using any free link to the switching circuit the data is send to the
switching circuit.
 Entire message is sent to the destination. It reaches through different
intermediate nodes following the “store and forward” approach.
 No dedicated connection is required.

36. Message Switching

37. Packet Switching
 Packet switching introduces the idea of cutting data i.e. at the source entire
message is broken in smaller pieces called packets which are transmitted
over a network without any resource being allocated.
 Then each packet is transmitted and each packet may follow any rout
available and at destination packets may reach in random order.
 At the destination when all packets are received they are merged to form
the original message.
 In packet switching all the packets of fixed size are stored in main memory.

38. Packet Switching

39. Data Channel
 Channel is the medium used to carry information from one point to another

40. Baud
 It is the unit of measurement for information
carrying capacity of the communication channel
 The baud is synonymous with bps
 Another unit of measuring data transfer rates
 bps- Bits per second
 Bps- Bytes per second
 kbps- kilo bits per second
 Kbps – Kilo bytes per second
 mbps-mega bits per second
 Mbps-Mega bytes per second

41. Communication Channel (Transmission
media):
 A communication channel is either a physical
transmission medium such as a wire, or to a
logical connection over a multiplexed medium
such as a radio channel in telecommunications
and computer networking.

42. Bandwidth:
 The amount of data that can be transferred from one point to
another.
 it is a measure of the range of frequencies a transmitted signal
occupies.
 In digital systems, bandwidth is the data speed in bits per
second.
 In analog systems, bandwidth is measured in terms of the
difference between the highest-frequency signal component
and the lowest frequency signal component.

43. Data transfer rate:
 DTR is the amount of data in digital form that is moved from one place to
another in a given time on a network.
 Data rates are often measured in megabits (million bits) or megabytes
(millionbytes) per second.
 bps bits per second Bps bytes per second
 Kbps kilobits per second KBps kilo bytes per second
 Mbps megabits per second MBps megabytes per second
 Gbps giga bits per second GBps giga bytes per second
 Tbps tera bits per second TBps tera bytes per second

44. NETWORK TOPOLOGIES
 Layout of a network
 The pattern of interconnection
 Different types:
 The Star topology
 The Bus topology
 The Ring/Circular topology
 The Mesh topology
 The Tree topology

45. Network Topology -Factors
 Cost
 Flexibility
 Realiability

46. Point to point Link
 Transmit and receive
 Transmit and receive occur over separate
wires
 Simple topology
A B

47. 1. The Star Topology
 This topology consists of a central node/ concentrator to which other
nodes are connected.
 There is a dedicated connection to all computers.

48. Advantages and Disadvantages
 Advantages:
 Easy to install & remove
 Easy to detect faults
 Disadvantages:
 Requires more cable length
 Central node dependency
 Expensive

49. 2. The Bus Topology
 A single length of the transmission medium on which various nodes
are attached.
 It transmits data from one end to another and can be received by
other station
 At each end there are terminators.

50. Advantages and Disadvantages
 Advantages:
 Easy to connect
 Less cable length
 Disadvantages:
 Main cable fails, everything fails
 Terminators are required at both ends

51. 3. The Ring Topology
 Each node is connected to two and only two neighboring nodes.
 Data travels in one direction only

52. Advantages and Disadvantages
 Advantages:
 Cheaper to install and expand
 Disadvantages:
 Troubleshooting is difficult
 Adding and deleting the computer disturbs the network
 Failure of one computer affects the whole network

53. 4. The Mesh Topology
 Each node is connected to more than one nodes in the network
directly

54. Advantages and Disadvantages
 Advantages:
 It is robust
 Fault is diagnosed easly
 Provide Security & Privacy
 Disadvantages:
 Installation and configuration is difficult
 High cable cost
 Cost of maintenance is high

55. 5. The Tree/ Expanded Star Topology
 Tree topology combines characteristics of linear bus and star topologies

56. Advantages and Disadvantages
 Advantages:
 It uses P2P wiring
 Easy maintenance
 Easy fault detection
 Supported by hardware & Software venders
 Disadvantages:
 Backbone dependency
 Difficult to configure and wire

57. 5. Fully Connected
 When in a network each host is connected to
other directly
 There is a direct link between each host

58. NETWORK DEVICES/HARDWARES
 In the smooth functioning of a computer network, many devices or
hardware play important roles.

59. 59
Modem
 Modulator/Demodulator
 It converts an analog signals from a telephone or cable wire to a
digital signal
 Similarly it converts digital data from the computer or other devices
to an analog signal
 Internal modems
 External modems

60. RJ 45
 Registered Jack-45
 8 wire connector
 Used to connect computers on the LAN
 RJ45 is very much similar to standard telephone connector (RJ11)
 RJ11 is a 4 wire connector

61. NIC (Network Interface Card)
 NIC is a device that is attached to each workstations and the server.
 Helps the workstation to establish a connection with network
 NIC is also called:
 TERMINAL ACCESS POINT (TAP)
 Network Interface Unit (NIU)
 MAC Address- Physical Address of NIC card
 MAC (Media Access Control)

62. MAC Address
 The NIC manufacturer assigns a unique physical address to
each NIC card.
 Media Access Control address (MAC address) is a unique
identifier
 assigned to a network interface controller (NIC)
 for use as a network address in communications within
a network segment.

64. Ethernet Card
Ethernet card is a type of NIC CARD
While NIC is the generic “Network Interface Card” which could be for different
types of network topologies like Ethernet, Token Ring, Fibre channel, infra red etc
Ethernet card is a type of NIC, which is specific to Ethernet technology
The computers that are part of Ethernet, have to install a special card called
Ethernet Card
An Ethernet card contains connections for:
Coaxial
twisted pair
or both

65. Hub
 Hub is used to connect several computers together
 A similar term is concentrator
 A concentrator is a device that provides a central connection point for cables
from workstations, servers and peripherals
 Hubs can be either
 Active Hub
 Passive Hub

66. Switch
 Switch is used to segment networks into different sub networks called subnets
or LAN segments
 Prevents traffic overloading in a network
 A switch is responsible for filtering
 LANs that are segmented through switches are called switched LANs.
 The switch establishes a temporary connection between the source and
destination.

67. Bridge
 Bridge is a device that lets you link two networks together.
 Bridges can handle networks that follow same protocols

68. Router
 A device that works like a bridge but can handle different protocols
 Routers can help ensure that packets are travelling the most efficient paths
to their destinations.
 A router uses logical address
 Bridges uses physical address

69. Wi-Fi Card
 Wi-Fi card allows you to setup wireless network access.
 A wi-fi card is either an internal or external

70. Gateway
 A gateway is a device that connects dissimilar networks
 A node on a network that serves as an entrance to another network
 The gateway node is often acts as a proxy server and a firewall

71. Access point
 Access point (AP) is also called Wireless Access Point(WAP)
 Access point is a hardware device that establishes connections of computing
devices on wireless LAN with a fixed wire network.
 Advantages:
 Easier installation
 Easier maintenance
 Bigger network coverage
 Stable signals
 Ease of network

72. The Cloud Computing
 Internet based computing
 The delivery of computing resources from a remote location
 The use of internet for the tasks you perform on your computer
for storage, retrieval and access

73. Different types
1. Public Cloud
2. Private Cloud
3. Hybrid Cloud
4. Community Cloud

74. (a) Public Cloud
 The resources such as memory, hardware
resources and network devices are shared by
all.
 Example:
 Google Drive
 Amazon Cloud
 Microsoft OneDrive etc.

75. (b)Private Cloud
 Private cloud is a virtual
Private interface provided by
individual or owned by one
organization

76. (c) Hybrid Cloud
 When single organization adopts both private & public
clouds for a single application.

77. (d) Community Cloud
 These clouds for use by a group of related organizations who
wish to make use of a common cloud computing environment.

78. Internet of Things (IoT)
 IoT the whole way of collecting data, processing it, taking action
corresponding to the signification of data to storing everything in the cloud.
 Designed to computerize and control most of the surrounding objects &
have access to data in real time.

79. Enabling Technologies of IoT
1. RFID (Radio Frequency Identification)
2. Sensors
3. Smart technologies
4. Software
5. Efficient Network connectivity

80. Devices that can form IoT
1. Home appliances
2. Wearables
3. Factories
4. Agriculture
5. Food

81. Challenges
 Like other networks, cyber attacks, hackers and unauthorized
intruders can attack IoTs as well

82. TRANSMISSION MEDIA
 Transmission media is a communication channel
that carries the information from the sender to
the receiver.
 Guided Media (cables)
 Unguided Media (Waves through- air, water or
vacuum)

83. Twisted Pair Cable
 Common form of wiring
 VGM –basis of most internal office telephone wiring
 Two identical wires wrapped together in a double helix
 Twisting of wire reduces crosstalk (bleeding of signal from one wire to
another)
 Also protects it from other external forms of interface is called crosstalk
 Advantages:
 Simple
 Easy to install and maintain
 Flexible
 Low weight
 inexpensive
Disdvantages:
 Incapable carrying a signal over long distance
 Low bandwidth
 Max data rate 1Mbps -10Mbps

84. Types of Twisted Pair Cables
(a)Unshielded Twisted Pair (UTP)
 Used for variety of electronic communications
 Available in 8 categories
 Maximum segment length of 100meters
(b)Shielded Twisted Pair (STP)
 comes with shielding of individual pairs of wires
 Max Segment length of 100 meters
 it offer greater protection from interference
 Heavier than UTP

85. Coaxial Cable
 Solid wire core sorrounded by one or more foil or wire shields each seperated by
some kind of plastic insulator
 Inner core carries the signal
 Coaxial cable has high electrical properties and is suitable for long distance
communication
 Widely used for TV signals
 Advantages:
 Better than Twisted Pair Cable
 Used for shared cable network
 Used for broadband transmission
 Offer higher band width upto 400Mbps
Disadvantages:
 Expensive
 Coaxial cable are not compatible with Twisted Pair cables

86. Types of Coaxial Cables
Thicknet
Thicker than thinnet
Segment length upto 500meters
Thinnet
Max. segment length upto 180meters

87. Optical Fiber Cable (OFC)
 Consists of thin strands of glass or glass like material
 Which are so constructed that they carry light signals from a source at one
end of the fiber to a detector at the other end
 Light sources- LED/ Laser Diodes(LD)
 High bandwidth
 LEDs – range between 20 and 150Mbps
 Higher rates are possible using LDs
Advantages:
 Immune to electrical and magnetic interface
 Suitable for harsh environments
 Secure
Disadvantages:
Installation problem- Fragile
Joining is difficult
Impossible to tap
Expensive

88. Types of OFC
 Single Node
 Segment length upto 2kms
 Bandwidth upto 100Mbps
 Multinode
 Segment Length upto 100Kms
 Bandwidth upto 2Gbps

89. Micro Wave (Terrestrial Microwave)
 Wireless Communication Media
 Micro wave signals are similar to radio/Tv signals
 Used for long distance communication
 Micro Wave Transmission consists of – Transmitter, Atmosphere and receiver
 Micro wave parabilic antinas used to send/ receive signals
 Higher the tower, greater the range
 Advantages:
 Cheaper than wired medium
 Free from land acquisition rights
 Ease of communication over difficult terrain
 Ability to communicate over oceans
Disadvantages:
 Insecure
 Susceptible to weather effects (rain, thunder storms etc)
 Cost of design and implementation and maintenance is high

90. Radio Wave
 Radio Frequencies used for the communication
 Use continuous Sine waves to transmit information (Audio, Video or data)
 Different radio signals use different sine wave frequency
 ANY RADIO SETUP HAS TWO PARTS:
 The Transmitter
 The receiver
 Advantages:
 Offers Mobility
 Cheaper than digging trenches for laying cables
 It offers freedom from land acquisition rights
 Ease of communication over difficult terrain
Disadvantages:
 Insecure communication
 Susceptible to weather effects (rain, thunder storms etc)

91. Satellite
 Satellite communication is special case of microwave relay system
 Time saving, fast implementation and broad coverage
 Satellites act as relay stations for communication signals
 Satellite accept data/signals transmitted from an earth station, amplify them
and retransmit to another earth station
 Advantages:
 Large coverage
 Suitable for inter continental communication
Disadvantages:
High investment cost
High atmospheric losses above 30GHz

92. Other Unguided Media
1. Infrared
1. This type of transmission uses IR light to send
data
2. TV Remotes, automotive garage doors,
wireless speakers
3. Will not penetrate walls
2. Laser
1. Transmission uses laser light to send data
2. Requires direct line of sight
3. Unidirectional, has much higher speed than
microwaves
4. Laser transmitter-> photo sensitive receiver

93. Wi-Fi (Wireless Fidelity)
 Wi-Fi is a wireless technology
 Allows devices such as computers, smart phones and other interface with
internet

94. Wi-Fi Hot Spot
 A venue that offers Wi-Fi

95. Network Protocols
 Network protocols are sets of rules and regulations that dictate
how to format, transmit and receive data on computer network
devices
 Like servers, routers to endpoints
 Can communicate regardless of the differences in their
infrastructures, designs or standards.
 To successfully send or receive information, network devices
must accept and follow protocol conventions .

96. Various protocols used in networks
 HTTP
 FTP
 TCP/IP
 SLIP/PPP

97. HTTP(Hypertext Transfer Protocol)
 HTTP means Hyper Text Transfer Protocol.
 HTTP is the underlying protocol used by the World
Wide Web
 This protocol defines how messages are formatted
and transmitted,
 and what actions Web servers and browsers should
take in response to various commands.
 For example, when you enter a URL in your
browser, this actually sends an HTTP command to
the Web server directing it to fetch and transmit
the requested Web page.

98. FTP(File Transfer Protocol)
 The File Transfer Protocol (FTP) is a standard network
protocol used for the transfer of computer files between a
client and server on a computer network.
 FTP is most commonly used to download a file from a server
using the Internet or to upload a file to a server (e.g.,
uploading a web page file to a Web server).
 FTP is a client-server protocol that relies on two
communications channels between client and server: a
command channel for controlling the conversation and a
data channel for transmitting file content.
 Clients initiate conversations with servers by requesting
to download a file. Using FTP, a client can
upload, download, delete, rename, move and copy files on a
server.

99. TCP/IP
 Transmission Control Protocol/ Internet Protocol
 TCP/IP stands for Transmission Control Protocol/Internet
Protocol and is a suite of communication protocols used to
interconnect network devices on the internet.
 TCP is responsible for :
 Dissembling/Assembling data
 IP is responsible for :
 Routing packets

100. SLIP/PPP
 Serial Line Internet Protocol(SLIP)
 Protocol for relaying IP packets over dial-up lines/dedicated links
 Point to Point Protocols(PPP)
 Internet Standard for transmission of IP packets over serial lines
 PPP is currently the best solution for dial-up connections including
ISDN (Integrated Services Digital Network)

101. Protocols used in Email
 In order to deal with your email, you must use an
email client to access a mail server
 The email client and server can exchange information
with each other using variety of protocols:
 IMAP
 POP3
 SMTP
 HTTP

102. IMAP
 Internet Message Access Protocol
 Standard protocol for accessing email from local
server Works well over a slow connection such as
a modem

103. POP3
 Post Office Protocol-3
 Simple, standardized way for users
to access mail boxes and download
message to their computers
 When using POP protocol, all the
emails get downloaded from the
email server to users local computer
 User can cut the internet connection
and read email

104. SMTP
 Simple Mail Transfer Protocol
 Used to when you send email to another email users.
 Used by Mail Transfer Agent(MTA) to deliver sent email to
recipient’s email server
 SMTP can only be used to send emails, not to receive them

105. Working of E-Mail
 What happens after you click the send button:
1. You compose and send an email from your mail client. Your email has the
recipients email address along the email message
2. your email client connects to the outgoing SMTP server and hands over the
email
3. Outgoing SMTP first validates the sender details.
4. DNS server finds the recipient’s server domain information.
5. Then SMTP server connects with the recipient email server and sends the
email through SMTP protocol
6. The recipient server validates the recipient account and delivers the email
to the users email account
7. The user logs into own email account and views the received mail using
email client uses POP3/ IMAP protocol

106. Working of E-Mail- Example

107. Telnet
 Remote desktop application
 Lets you log on to remote computer systems
 Telnet program gives you a character-based
terminal window on other system
 If you have permitted access, you can work on
that system
 (Similar Application-AnyDesk, Teamviewer)

108. HTTP
 Hyper Text Transfer Protocol
 Not a protocol dedicated for email
communications
 But it can be used to access mailbox.
 Also called web based email, this protocol can be
used to compose or retrieve emails from email
account.
 Gmail, Ymail, Hotmail etc are good examples of
using HTTP as an email protocol

109. How HTTP Works
Whenever you enter a URL in the address box of the browser, The web
browser displays the intended URL’s website or sometimes error
message.
Internally,
1. Web browser (HTTP client) translates the URL into HTTP request
2. Sends the HTTP request to the server.
3. Server respond to HTTP requests
In other words, the web communication between a host/server and a
client occurs, via an HTTP request/response pair.

110. Let us see HTTP actually works
 The request message (HTTP request) is sent to an HTTP server
 HTTP server receives the HTTP request, fetches the
information as per the request and send it to HTTP client
 HTTP client receives the response message, interprets the
message and displays the content of the message on browser’s
window.

111. HTTPS
• Hypertext Transfer Protocol Secure (HTTPS) is an extension
of the Hypertext Transfer Protocol (HTTP).
• HTTPS is HTTP with encryption and verification.
• An HTTPS URL begins with https:// instead of http://.
• Most web browsers show that a website is secure by
displaying a closed padlock symbol to the left of the URL in
the browser's address bar.

112. VoIP
 Voice over Internet Protocol
 Voice over Internet Protocol (VoIP), is a technology that allows
you to make voice calls using a broadband Internet
connection instead of a regular (or analog) phone line.
 The most popular examples of VoIP services are Skype and
Whatsapp.

113. Wireless Vs. Mobile Computing

114. Wireless/ Mobile
Computing Technologies
 GSM:
 Global System for Mobile Communication
 One of the leading cellular systems established in the mid of 1980’s
 SIM- Subscriber Identification Module
 SIM cards are small removable disks that slip in and out of GSM phones
 They store all connection data and identification numbers.
 GSM uses narrowband TDMA (Time Division Multiple access)-8 users can use
same frequency at a time
 GSM use encryption to make phone calls secure

115. Wireless/ Mobile Computing
Technologies
 CDMA- Code Division Multiple Access
 Digital cellular technology
 CDMA does not assign a specific frequency to each
user
 Every channel uses the full available spectrum
 CDMA is a military technology first used during
World War II

116. Wireless/ Mobile Computing
Technologies
 WLL - Wireless in Local Loop(WiLL or WLL)
 Each customer is equipped with a mini station of low power, into
which the telephone is connected.
 Will unit consist of a radio transceiver and the WLL interface
assemble in one metal box
 When calls are made from the telephone, it signals the base
station for a connection, which is subsequently established
through a switch centre.
 Incoming calls is identified at the switch center and routed to the
base station assigned

117. Wireless/ Mobile Computing
Technologies
 GPRS- General Packet Radio System
 GPRS is a technology for radio transmission of small packets of data
especially between mobile devices and internet
 You can access Internet, Send Emails, and large data, Watch real time
News, download games and watch movies
 Packet switching method

118. Cellular/ Wireless Connectivity Protocols
 Various Wireless technologies:
 1G
 2G
 3G
 4G
 5G

119. 1G- First Generation
 First generation wireless technology
 Introduced in US in early 1980’s
 Designed exclusively for voice communication

120. 1G- Characteristics
 Speeds up to 2.4kbps
 Poor voice quality
 Large phones with limited battery life
 No data security

121. 2G- Second Generation
 Second generation of mobile technology
 Used digital signals
 Launched in Finland in 1992
 Used GSM(Global System for Mobiles) technology.
 SMS support

122. 2G- Characteristics
 Data speed up to 250kbps
 Text, Multimedia messaging support
 Better voice quality
2G along with GPRS technology is known as 2.5 G

123. 3G- Third Generation
 Introduced in 2000
 Web browsing, email, video downloading, picture
sharing and other SMART PHONE technology

124. 3G- Characteristics
 Data speed up to 20 Mbps
 High quality voice transmission
 Supported multi media
 Mobile TV, Mobile internet

125. 4G- Fourth Generation
 Introduced in 2013
 Data speed up to 100 Mbps

126. 4G- Characteristics
 Support interactive multi media
 High speed
 High capacity
 Low cost
 High voice quality

127. 5G- Fifth Generation
 It is the yet to be implemented wireless technology
 New global wireless standard after 4G
 Multi Gbps data speeds
 More reliable
 Massive network capacity

128. Internetworking terms and services
 www
 Telnet
 Web Browser and Web Server
 Web Sites, Web Address and Web Pages
 URL and Domain Names
 Web Hosting
 Web 2.0
 HTML
 XML
 DHTML

129. WWW(World Wide Web)
 The World Wide Web—commonly referred to as WWW, W3, or the Web
 —is an interconnected system of public webpages accessible through the
Internet.
 The Web is not the same as the Internet: the Web is one of many applications
built on top of the Internet.
 WWW Attributes
 User friendly
 Multimedia Documents
 Hypertext and Hyperlinks
 Interactive
 Frames
Click me!

130. Web Browser and Web Server
 A web browser is a www client that navigates
through the world wide web and displays web
pages
 Web server is a www server that responds to the
requests made by the web browsers

131. Web Sites & Web pages
Website
 A collection of web pages which are grouped together and usually connected together
in various ways. Often called a "web site" or a "site.“
 To access a website, type its domain name in your browser address bar, and the
browser will display the website's main web page, or homepage (casually referred as
"the home")
web page
 A document which can be displayed in a web browser such as Firefox, Google Chrome,
Opera, Microsoft Internet Explorer or Edge, or Apple's Safari. These are also often
called just "pages.“
 A web page is a simple document displayable by a browser. Such documents are
written in the HTML language
 Home Page: top-level web page of a web site
 Web Portal: Web Sites which hosts other web sites (eg: www.yahoo.com)

132. Web Address
 The web address contains information about the location
of the webpage.
 It is also known as the URL (uniform resource locator).
 Like the address for your home, a web address organizes
information about a webpage's location in a predictable way.
 URLs Look like: type://address/path
 Eg: http://encycle.msn.com/getinfo/styles.asp
 ftp://ftp.prenhall.com
 http://www.yahoo.com
 news://alt.tennis

133. Elements of URLs
 The type of server
 The name /address of the server
 The location of the file(Path)
Some common Domains:
com - Commercial
edu - Educational
gov - Government
mil - Military
org - Organization
http://microsoft.co.in
in – Site is based in India
au - Australia
dk - Denmark
nz - New Zealand
ca - Canada
f
jp - Japan
uk - United Kingdom

134. HTML
 Hyper Text Markup Language
 HTML is the standard markup language for
documents designed to be displayed in a web
browser.
 Commands used in HTML programming is called
Tags

135. XML
 eXtensible Markup Language
 For documents containing structured information
 A markup language is a set of codes, or tags, that describes the text in a digital document
 Is a standard markup language that defines other markup languages.
 Used for transferring data.
 Dynamic in nature.
 HTML and XML are related to each other:
 HTML displays data and describes the structure of a webpage, whereas XML stores and
transfers data.
 HTML is a simple predefined language, while XML is a standard language that defines other
languages.
 HTML is used to displaying data
 HTML is Static

136. DHTML
 Dynamic HTML
 DHTML, is a collection of technologies used together to
create interactive and animated websites by using a
combination of a static markup language (such as HTML),
a client-side scripting language (such as JavaScript), a
presentation definition language (such as CSS)
 DHTML is a combination of Web development
technologies used to create dynamically changing
websites.

137. Web Hosting
 A web hosting service is a type of Internet hosting
service that hosts websites for clients
 i.e. it offers the facilities required for them to create and
maintain a site and makes it accessible on the World Wide
Web.
 Companies providing web hosting services are sometimes
called web hosts.
 Types:
 Free Hosting
 Virtual or Shared Hosting
 Dedicated hosting
 Co-Location Hosting

138. Free Hosting
 This is a free non-paid web hosting service. This type of hosting is available with
many prominent sites that offer to host some web pages for no cost.
 Advantages :
 Free of cost
 Use websites to place advertisements, banners and other forms of advertising
media
 Disadvantages:
 Customer support is missing
 Low bandwidth and lesser data transfer
 No control over your website

139. Shared/Virtual Hosting
 Its a web hosting service where many website reside on one web server connected to the
internet.
 This type of hosting is provided under one’s own domain name, www.yourname.com.
 With a hosting plan with the wed b hosting company, one can present oneself as a fully
independent identity to his/her web audience.
 Advantages :
 Easy and affordable
 Secured by hosting provider
 24/7 Technical support
 Disadvantages:
 Shared resources can slow down the whole server
 Less flexible than dedicated hosting

140. Dedicated Hosting
 Hosted on a dedicated server, this type of hosting is best suited for large websites with high
traffic.
 In this, the company wishing to go online, rents an entire web server from a hosting company.
 This is suitable for companies hosting larger websites, maintaining other’s sites or managing a
big online mall etc.
 Advantages :
 Ideal for large business
 Strong database support
 Unlimited software support
 Disadvantages:
 Its very expensive

141. Co-located Hosting
 This hosting lets you place your own web server on the
premises of a service provider.
 It is similar to that of dedicated hosting except for the fact
that the server is now provided by the user-company itself
and its physical needs are met by the hosting company.
 Advantages :
 Greater Bandwidth High Up-Time
 Unlimited Software Options
 High Security
 Disadvantages:
 Its expensive

142. Web 2.0
 Refers to added features and applications that make the web
more interactive, Support easy online information exchange and
interoperability
 Example:
 Facebook
 Blogger
 WordPress
 Youtube
 Flickr

143. Web Scripting
 Web script, a computer programming language for
adding dynamic capabilities to World Wide Web pages.
 Process of creating and embedding scripts in a web page is
known as web-scripting
 Script- is a computer script is a list of commands that are
embedded in a web-page
 Java Script, PHP, PERL,JSP etc
 Client Side Scripts
 Server- Side Script