Class xii computer networking ppt in detail

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 Share Resources ( Eg -Printer Sharing) Share storage Can share software ( Eg -Software can be installed centrally) 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 A dvanced R esearch P rojects A gency NET work 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

25. 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)

26. 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

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

28. Let us see how internet functions

29. 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.

30. 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

31.   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

32. 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.

33. Circuit Switching

34. 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.

35. Message Switching

36. 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.

37. Packet Switching

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

39. 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

40. 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.

41. 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 .

42. 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

43. 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

44. Network Topology -Factors Cost Flexibility Realiability

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

46. 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.

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

48. 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.

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

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

51. 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

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

53. 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

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

55. 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

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

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

58. 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 59

59. 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

60. 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)

61. MAC Address The NIC manufacturer assigns a unique physical address to each NIC card.   M edia A ccess C ontrol 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 .

62. 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

63. 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

64. 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.

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

66. 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

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

68. 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

69. 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

70. 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

71. Different types Public Cloud Private Cloud Hybrid Cloud Community Cloud

72. (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.

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

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

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

76. 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.

77. Enabling Technologies of IoT RFID (Radio Frequency Identification) Sensors Smart technologies Software Efficient Network connectivity

78. Devices that can form IoT Home appliances Wearables Factories Agriculture Food

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

80. 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)

81. 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

82. Types of Twisted Pair Cables Unshielded Twisted Pair (UTP) Used for variety of electronic communications Available in 8 categories Maximum segment length of 100meters 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

83. 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

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

85. 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

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

87. 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

88. 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 )

89. 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

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

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

92. Wi-Fi Hot Spot A venue that offers Wi-Fi

93. 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 .

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

95. HTTP(Hypertext Transfer Protocol) HTTP means H yper T ext T ransfer P rotocol. HTTP is the underlying protocol used by the World Wide Web T his 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.

96. 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.

97. 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

98. 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)

99. 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

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

101. 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

102. SMTP S imple M ail T ransfer P rotocol 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

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

104. Working of E-Mail- Example

105. 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 )

106. 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

107. 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, Web browser (HTTP client) translates the URL into HTTP request Sends the HTTP request to the server. 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.

108. 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.

109. 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.

110. 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 . 

111. Wireless Vs. Mobile Computing

112. 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

113. 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

114. 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

115. 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

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

117. 1G- First Generation First generation wireless technology Introduced in US in early 1980’s Designed exclusively for voice communication

118. 1G- Characteristics Speeds up to 2.4kbps Poor voice quality Large phones with limited battery life No data security

119. 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

120. 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

121. 3G- Third Generation Introduced in 2000 Web browsing, email, video downloading, picture sharing and other SMART PHONE technology

122. 3G- Characteristics Data speed up to 20 Mbps High quality voice transmission Supported multi media Mobile TV, Mobile internet

123. 4G- Fourth Generation Introduced in 2013 Data speed up to 100 Mbps

124. 4G- Characteristics Support interactive multi media High speed High capacity Low cost High voice quality

125. 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

126. 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

127. 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!

128. 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

129. 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)

130. 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

131. 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

132. 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

133. 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

134. 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.

135. 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

136. 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

137. 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

138. 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

139. 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

140. 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

141. 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