Networking / Internet and Web Technologies


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Computer network is nothing but a set of computers connected to each other, mainly for sharing information,data, programs and resources. Networking reduces the cost of doing business since resources are utilized to maximum extent. Broad categories of networking are LAN,WAN,MAN,STAR,BUS, Ring Topology among others.

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Networking / Internet and Web Technologies

  1. 1. I.T. for Management Chapter 5 Networking/Internet & Web technologies
  2. 2. Networking• The Computer Network is nothing but a set of computers connected to each other, mainly for Sharing information, data, programs & resources.• Networking reduces the cost of doing business since resources are utilized to optimum extent.• The evolution of newer business models such as the ITES/BPO,the offshore Software etc are an outcome of the Networks be it in Telephony or in terms of computer networks.
  3. 3. Networking • Benefits• Interaction & communication between various people at locations & perhaps using different types of hardware& software different• Sharing of Data so that there is consistency of data• Sharing of expensive devices such as printers• Created newer and previously unthinkable ways of doing business such as telecom,BPO etc.
  4. 4. Networking• Broad categories of networking are LAN, WAN, MAN Cu Cable, Fiber Cable, Wireless TCP/IP, HTTP Protocols Star, Bus, Ring Topology Packet Switching/Network switching Peer to Peer Network
  5. 5. Network Topologies What is a Topology? The physical topology of a network refersto the configuration of cables, computers,and other peripherals.Physical topology should not be confusedwith logical topology which is the methodused to pass information betweenworkstations
  6. 6. Network Topologies Main Types of Physical Topologies The following sections discuss the physical topologies used in networks and other related topics.• Linear Bus• Star• Star-Wired Ring• Tree
  7. 7. Network TopologiesLinear BusA linear bus topology consists of a main run ofcable with a terminator at each end (See fig. 1).All nodes (file server, workstations, andperipherals) are connected to the linear cable.Ethernet and LocalTalk networks use a linearbus topology.
  8. 8. Network Topologiesdvantages of a Linear Bus Topology Easy toconnect a computer or peripheral to a linear bus. Requires less cable length than a star topology.isadvantages of a Linear Bus Topology Entire network shuts down if there is a breakin the main cable. Terminators are required at both ends of thebackbone cable. Diffi lt t id tif th bl if th ti
  9. 9. Network Topologies Star A star topology is designed with each node (file server,workstations, and peripherals) connected directly to a centralnetwork hub or concentrator (See fig. 2). Data on a star network passes through the hub orconcentrator before continuing to its destination. The hub or concentrator manages and controls allfunctions of the network. It also acts as a repeater for thedata flow. This configuration is common with twisted pair cable;however, it can also be used with coaxial cable or fiber opticcable.
  10. 10. Network Topologiesdvantages of a Star Topology Easy to install and wire. No disruptions to thenetwork then connecting orremoving devices.isadvantages of a Star Topology Easy to detect faults and toremove parts. Requires more cable length than alinear topology. If the hub or concentrator fails,nodes attached are disabled. More expensive than linear bus
  11. 11. Network TopologiesTreeA tree topology combinescharacteristics of linear bus andstar topologies. It consists ofgroups of star-configuredworkstations connected to alinear bus backbone cable (Seefig. 4). Tree topologies allowfor the expansion of an existingnetwork, and enable schools toconfigure a network to meettheir needs.
  12. 12. Components of a Network• The Computers are connected to the medium with the help of network interface cards(NIC)• One of the computers on the network is designed as controller usually called as Server• Sever usually maintains vital information about network,• Holds shared software& services• Monitors facilities so that problems on network can be detected& corrected• It act as intelligent device which routes the message to the appropriate path
  13. 13. Networking Devices• Common basic network devices: Gateway: device sitting at a network node for interfacing with another network that uses different protocols. Works on OSI layers 4 to 7. Router: a specialized network device that determines the next network point to which to forward a data packet toward its destination. Unlike a gateway, it cannot interface different protocols. Works on OSI layer 3. Bridge: a device that connects multiple network segments along the data link layer. Works on OSI layer 2.
  14. 14. Networking DevicesSwitch: a device that allocates traffic from one networksegment to certain lines (intended destination(s)) whichconnect the segment to another network segment. Sounlike a hub a switch splits the network traffic and sendsit to different destinations rather than to all systems onthe network. Works on OSI layer 2.Hub: connects multiple Ethernet segments togethermaking them act as a single segment. When using ahub, every attached device shares the same broadcastdomain and the same collision domain. Therefore, onlyone computer connected to the hub is able to transmit ata time.
  15. 15. Networking DevicesDepending on the network topology, the hubprovides a basic level 1 OSI model connectionamong the network objects (workstations,servers, etc). It provides bandwidth which isshared among all the objects, compared toswitches, which provide a dedicated connectionbetween individual nodes. Works on OSI layer 1.Repeater: device to amplify or regenerate digitalsignals received while setting them from onepart of a network into another. Works on OSIlayer 1.
  16. 16. Network CablingWhat is Network Cabling?Cable is the medium through which informationusually moves from one network device toanother. There are several types of cable whichare commonly used with LANs. In some cases, anetwork will utilize only one type of cable, othernetworks will use a variety of cable types. Thetype of cable chosen for a network is related tothe networks topology, protocol, and size.Understanding the characteristics of differenttypes of cable and how they relate to otheraspects of a network is necessary for thedevelopment of a successful network
  17. 17. Network CablingUnshielded Twisted Pair (UTP) CableTwisted pair cabling comes in two varieties:shielded and unshielded. Unshielded twistedpair (UTP) is the most popular and is generallythe best option for school networks(See fig. 1).
  18. 18. Network CablingCoaxial CableCoaxial cabling has a single copperconductor at its center. A plastic layerprovides insulation between the centerconductor and a braided metal shield (Seefig. 3). The metal shield helps to block anyoutside interference from fluorescent lights,motors, and other computers.
  19. 19. Network CablingFiber Optic CableFiber optic cabling consists of a center glass coresurrounded by several layers of protective materials(See fig. 5).It transmits light rather than electronic signalseliminating the problem of electrical interference. Thismakes it ideal for certain environments that contain alarge amount of electrical interference. It has also madeit the standard for connecting networks betweenbuildings, due to its immunity to the effects of moistureand lighting.
  20. 20. Network Cabling MaximumSpecificatio Cable Type length n10BaseT Unshielded Twisted 100 meters Pair10Base2 Thin Coaxial 185 meters10Base5 Thick Coaxial 500 meters10BaseF Fiber Optic 2000 meters100BaseT Unshielded Twisted Pair 100 meters100BaseT Unshielded Twisted 220 metersX Pair
  21. 21. Network Cabling Wireless LANsNot all networks are connected with cabling; some networksare wireless. Wireless LANs use high frequency radiosignals, infrared light beams, or lasers to communicatebetween the workstations and the file server or hubs. Eachworkstation and file server on a wireless network has somesort of transceiver/antenna to send and receive the data.Information is relayed between transceivers as if they werephysically connected. For longer distance, wirelesscommunications can also take place through cellulartelephone technology, microwave transmission, or bysatellite.
  22. 22. Network Cabling Wireless LANsWireless networks are great for allowing laptopcomputers or remote computers to connect to theLAN. Wireless networks are also beneficial in olderbuildings where it may be difficult or impossible toinstall cables.
  23. 23. How do Networks Work Once the physical connection between computers areestablished ,computers can send messages to each other A computer wishing to communicate with anotherneeds to do what is known as a “hand Shaking” All these rules for communication is called protocols There are various protocols at various levels of software In practice there are different layers of software eachperforming different functions There is a well known international model defined byInternational Standards Organization
  24. 24. How do Networks Work OSI Model Data unit Layer Function Application Network process to application Data Presentation Data representation and encryption Hostlayers Session Inter host communication Segments Transport End-to-end connections and reliability (TCP) Packets Network Path determination and logical addressing (IP)Media Frames Data link Physical addressing (MAC & LLC)layers Bits Physical Media, signal and binary transmission
  25. 25. How do Networks Work Packet switching, in computer networking and telecommunications, is the communications paradigm in which packets (units of information carriage) are routed between nodes over data links shared with other traffic. This contrasts with the other principal paradigm, circuitswitching, which sets up a dedicated connection between the two nodes for their exclusive use for the duration of thecommunication. Packet switching is used to optimize the use of the bandwidth available in a network, to minimize the transmission latency (i.e. the time it takes for data to pass across the network), and to increase robustness of communication.
  26. 26. How do Networks WorkPacket routingPackets are routed to their destination as determined by arouting algorithm. The routing algorithm can create pathsbased on various metrics and desirable qualities of therouting path. For example, low latency may be of paramountconcern and everything else is secondary, or a minimumhop count.Its also entirely possible to have to weigh the variousmetrics against each other. For example, reducing the hopcount could increase the latency to an unacceptable limitand some kind of balance would need to be found. Formulti-parameter optimization, some form of optimizationmay be needed.
  27. 27. How do Networks WorkA peer-to-peer system is a distributed system whosecomponent nodes participate in similar roles, and aretherefore peers to each other. Peer-to-peer can beviewed as decentralized network architecture. Incontrast, a client-server architecture implies a sharpdistinction between the clients which request andconsume services, and servers which provide services.Even though the nodes have similar roles, there maystill be some structure to the peer-to-peer system, and itusually possesses some degree of self-organizationwhere each node finds its peers and helps maintain thesystem structure. ……. Cont
  28. 28. How do Networks WorkThis makes a peer-to-peer network node more complex than aclient in client-server system. The main benefits of peer-to-peersystem are scalability, fault-tolerance, and the lack of resourcebottlenecks in servers.The peer-to-peer concept is related to Distributed computing andSwarm intelligence, but differs from them in that peer-to-peernodes usually serve their own needs acting as Intelligent agents,instead of performing a collective function as a group.Recently, the concept has achieved recognition in the generalpublic in the context of peer-to-peer file sharing which is oneapplication of peer-to-peer networks.
  29. 29. Wi-Fi in campus For computers to use the wireless facility requires2 things Each computer must be fitted with wirelesscard.most Laptops tend to have this facility The server would send information thru a LAN.Awireless access point which is a special deviceisalso connected to the LAN This device converts the signals received from theLAN & broadcasts them into signal suitablefor LAN
  30. 30. Wi-Fi in campusAny products tested and approved as "Wi-Fi Certified" (aregistered trademark) by the Wi-Fi Alliance are certified asinteroperable with each other, even if they are from differentmanufacturers. A user with a "Wi-Fi Certified" product canuse any brand of access point with any other brand of clienthardware that also is certified. Typically, however, any Wi-Fiproduct using the same radio frequency (for example, 2.4GHzfor 802.11b or 11g, 5GHz for 802.11a) will work with anyother, even if not "Wi-Fi Certified.".
  31. 31. Wi-Fi in campus The Advantages of Wi-Fi in a campus It can be installed very easily& quickly no civilwork no cable laying, antenna can be deployed in asingle day User using laptops PDA can move devices toany locations without getting disconnected Thus it provides access anywhere,anytimewithin the campus This can increase productivity of the work force
  32. 32. Plain Old Telephone systems Short for plain old telephone service, which refers to the standard telephone service that most homes use. In contrast, telephone services based on high-speed, digital communications lines, such as ISDN and FDDI, are not POTS. The main distinctions between POTS and non-POTS services are speed and bandwidth. POTS is generally restricted to about 52 Kbps (52,000 bits per second). The POTS network is also called the public switched telephone network (PSTN).
  33. 33. Plain Old Telephone systems Plain old telephone service, or POTS, is a term which describes the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network nearly everywhere in the world. The name is a reflection of the telephone service still available after the advent of more advanced forms of telephony such as ISDN, mobile phones and VoIP. It has been available almost since the introduction of the public telephone system in the late 19th century, in a form mostly unchanged to the normal user despite the introduction of Touch-Tone dialing, electronic telephone exchanges and fiber-optic communication into the public switched telephone network (PSTN).
  34. 34. VSAT based networkA 2.5m parabolic dish antenna for bidirectionalSatellite Internet Access.A Very Small Aperture Terminal (VSAT), is a 2-way satellite ground station with a dish antenna thatis smaller than 3 meters. VSATs are mostcommonly used to transmit credit card or RFIDdata for point of sale transactions, and for theprovision of Satellite Internet access to remotelocations.
  35. 35. VSAT AdvantagesThe advances of computer technology have changed the satellite businesssituation of FSS (Fixed satellite services). This FSS satellite system has ahuge capacity with relatively low price system including prices forproviding VSATs terminal. This tendency causes the FSS system becomea very interesting business. Nowadays, the regulation of satellite servicesgoes to the subscribers using VSAT terminal. These FSS satellite systemsprovide various applications for subscribers. These applications are notonly limited in phone conversation, faximile, TV broadcast or high speedcommunication services, but also for new services such as direct to home(DTH), internet access, video conferencing, Satellite News Gathering(SNG), frame relay, Digital Audio Broadcasting (DAB) and others.Basically, these systems are applicable for providing various excellentquality services, because they create efficient communication system,both for home dwellers and business people.
  36. 36. ISDNIntegrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allowdigital transmission of voice and data over ordinarytelephone copper wires, resulting in better quality andhigher speeds than that available with the PSTN system.More broadly, ISDN is a set of protocols for establishingand breaking circuit switched connections, and foradvanced call features for the user.In a videoconference, ISDN provides simultaneous voice,video, and text transmission between individual desktopvideoconferencing systems and group (room)videoconferencing systems.
  37. 37. Advantages of ISDNThe purpose of the ISDN is to provide fullyintegrated digital services to the users. These services fall under three categories: bearerservices, supplementary services and teleservices.Being digital they carry signals without muchdistortionIt can carry all types of signals voice data &multimediaISDN is typically used for vedio conferance
  38. 38. InternetThe Internet is the worldwide, publicly accessiblenetwork of interconnected computer networks thattransmit data by packet switching using thestandard Internet Protocol (IP). It is a "network ofnetworks" that consists of millions of smallerdomestic, academic, business, and governmentnetworks, which together carry various informationand services, such as electronic mail, online chat,file transfer, and the interlinked Web pages andother documents of the World Wide Web.
  39. 39. Internet Protocols•IP (Internet Protocol), which defines the datagrams or packets thatcarry blocks of data from one node to another. The vast majority oftodays Internet uses version four of the IP protocol (i.e. IPv4), andalthough IPv6 is standardized, it exists only as "islands" ofconnectivity, and there are many ISPs without any IPv6 connectivity.[1]•Next come TCP (Transmission Control Protocol), UDP (UserDatagram Protocol), and ICMP (Internet Control Message Protocol) -the protocols by which data is transmitted. TCP makes a virtualconnection, which gives some level of guarantee of reliability. UDP isa best-effort, connectionless transport, in which data packets that arelost in transit will not be re-sent. ICMP is connectionless, it is used forcontrol and signaling purposes.•On top comes the application protocol. This defines the specificmessages and data formats sent and understood by the applicationsrunning at each end of the communication.
  40. 40. How does a dial up user get connected to internet The dial up users computer is not a host on theinternet.He has to connect to the internet serviceprovider such as VSNL After authenticating the user,VSNL server wouldassign a temporary IP number from a shared pool ofIP numbers Once your machine gets a temporary IP addressand is connected to internet via VSNL servers yourmachine becomes a host on the internet …..Cont
  41. 41. How does a dial up user get connected to internet Hence someone wishes to chat with you can typeyour temporary IP number & access your machine Once you log out of internet the IP number is deallocated & is available in the share pool with theservice provider The Worldwide web is the most popularapplication on the internet Hypertext Mark up language (HTML) provides astandard tag which identifies each block within document
  42. 42. Web ServerThe term Web server can mean one of two things: 1.A computer that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are Web pages such as HTML documents and linked objects (images, etc.). 2.A computer program that provides the functionality described in the first sense of the term. …… Cont
  43. 43. Web ServerAlthough Web server programs differ in detail, they allshare some basic common features. 1.HTTP: every Web server program operates by accepting HTTP requests from the network, and providing an HTTP response to the requester. The HTTP response typically consists of an HTML document, but can also be a raw text file, an image, or some other type of document; if something bad is found in client request or while trying to serve the request, a Web server has to send an error response which may include some custom HTML or text messages to better explain the problem to end users.Logging: usually Web servers have also the capability oflogging some detailed information, about client requests andserver responses, to log files; this allows the Webmaster tocollect statistics by running log analyzers on log files.
  44. 44. Web ServerThe inside/rear of a Dell PowerEdge web server, which is using theApache web server software
  45. 45. Web Server The web server & documents are located by auser with the help of uniform resourcelocator(URL) which is like web address The user types the URL on the search bar URL is converted into IP address of the webserver and the browser request is sent to the webserver The web server locates the document based onthe registration which information which it hasabout the document It sends document across internet to the IP address
  46. 46. Domain Names• The term domain name has multiple related meanings: A name that identifies a computer or computers on the internet. These names appear as a component of a Web sites URL, e.g. This type of domain name is also called a hostname. The product that Domain name registrars provide to their customers. These names are often called registered domain names.
  47. 47. Domain NamesThey are sometimes colloquially (and incorrectly) referred to by marketers as "web addresses".Names used for other purposes in the Domain Name System (DNS), for example the special name which follows the @ sign in an email address, or the Top-level domains like .com, or the names used by the Session Initiation Protocol (VoIP), or DomainKeys.
  48. 48. Domain Names• The following example illustrates the difference between a URL (Uniform Resource Locator) and a domain name:• URL:• Domain name:• Registered domain name: ……cont
  49. 49. Domain Names As a general rule, the IP address and the servername are interchangeable. For most Internetservices, the server will not have any way toknow which was used. However, the explosionof interest in the Web means that there are farmore Web sites than servers. To accommodatethis, the hypertext transfer protocol (HTTP)specifies that the client tells the server whichname is being used. This way, one server withone IP address can provide different sites fordifferent domain names.
  50. 50. HTTPShort for Hyper Text Transfer Protocol, theunderlying protocol used by the World Wide Web.HTTP defines how messages are formatted andtransmitted, and what actions Web servers andbrowsers should take in response to variouscommands. For example, when you enter a URL inyour browser, this actually sends an HTTPcommand to the Web server directing it to fetch andtransmit the requested Web page.
  51. 51. HTTPThe other main standard that controls how theWorld Wide Web works is HTML, which covershow Web pages are formatted and displayed.HTTP is called a stateless protocol because eachcommand is executed independently, without anyknowledge of the commands that came before it.This is the main reason that it is difficult toimplement Web sites that react intelligently to userinput. This shortcoming of HTTP is being addressedin a number of new technologies, includingActiveX, Java, JavaScript and cookies.
  52. 52. CookiesThe main purpose of cookies is to identify users and possiblyprepare customized Web pages for them. When you enter a Web site using cookies, you may be askedto fill out a form providing such information as your nameand interests.This information is packaged into a cookie and sent to yourWeb browser which stores it for later use.The next time you go to the same Web site, your browserwill send the cookie to the Web server.
  53. 53. Cookies The server can use this information to present you withcustom Web pages. So, for example, instead of seeing just ageneric welcome page you might see a welcome page withyour name on it.The name cookie derives from UNIX objects called magiccookies. These are tokens that are attached to a user or program andchange depending on the areas entered by the user orprogram
  54. 54. WebsitesA website (or Web site) is a collection of webpages, images, videos and other digital assets andhosted on a particular domain or subdomain on theWorld Wide Web.A web page is a document, typically written inHTML, that is almost always accessible via HTTP,a protocol that transfers information from thewebsites server to display in the users webbrowser.
  55. 55. WebsitesAll publicly accessible websites are seencollectively as constituting the "World Wide Web".The pages of websites can usually be accessed froma common root URL called the homepage, andusually reside on the same physical server. TheURLs of the pages organize them into a hierarchy,although the hyperlinks between them control howthe reader perceives the overall structure and howthe traffic flows between the different parts of thesites.
  56. 56. WebsitesSome websites require a subscription to accesssome or all of their content. Examples ofsubscription sites include many business sites, partsof many news sites, gaming sites, message boards,Web-based e-mail services, and sites providingreal-time stock market data.As of March 2007 there are over 110 millionwebsites in total on the world wide web.
  57. 57. WebsitesHistoryThe first on-line website appeared in 1991. On 30 April1993, CERN announced that the World Wide Web would befree to anyone..OverviewOrganized by function a website may be •a personal website •a business website •a government website or •a non-profit organization website.
  58. 58. WebsitesWebsites are written in, or dynamically convertedto, HTML (Hyper Text Markup Language) and areaccessed using a software program called a Webbrowser, also known as an HTTP client. Web pagescan be viewed or otherwise accessed from a range ofcomputer based and Internet enabled devices ofvarious sizes, including desktop computers, laptopcomputers, PDAs and cell phones.
  59. 59. WebsitesA website is hosted on a computer system known asa web server, also called an HTTP server, and theseterms can also refer to the software that runs onthese system and that retrieves and delivers the Webpages in response to requests from the website users.Apache is the most commonly used Web serversoftware
  60. 60. WebsitesA static website, is one that has web pages stored onthe server in the same form as the user will viewthem. They are edited using three broad categories ofsoftware: •Text editors. such as Notepad or TextEdit, where the HTML is manipulated directly within the editor program •WYSIWYG editors. such as Microsoft FrontPage and Macromedia Dreamweaver, where the site is edited using a GUI interface and the underlying HTML is generated automatically by the editor software
  61. 61. WebsitesTemplate-based editors, such as Rapidweaver andiWeb, which allow users to quickly create andupload websites to a web server without having toknow anything about HTML, as they just pick asuitable template from a palette and add pictures andtext to it in a DTP-like fashion without ever havingto see any HTML code.A dynamic website is one that has frequentlychanging information or collates information on thehop each time a page is requested. For example, itwould call various bits of information from adatabase and put them together in a pre-definedformat to present the reader with a coherent page.
  62. 62. Websites It interacts with users in a variety of ways includingby reading cookies recognizing users previoushistory, session variables, server side variables etc.,or by using direct interaction (form elements,mouseovers, etc.). A A site can display the currentstate of a dialogue between users, monitor achanging situation, or provide information in someway personalized to the requirements of theindividual user.
  63. 63. Websites Suppliers can now view The requirement of the customer Bid for the requirement Received a confirmed order from the customervia the Website Updates the information on deliveries sent to thecustomer Get acknowledgement & receive payment fordeliveries
  64. 64. Types of websitesThere are many varieties of Web sites, each specialising in a particular type of content or use, and they may be arbitrarily classified in any number of ways. A few such classifications might include:[original research?] Affiliate: enabled portal that renders not only its custom CMS but also syndicated content from other content providers for an agreed fee. There are usually three relationship tiers. Affiliate Agencies (e.g., Commission Junction), Advertisers (e.g., Ebay) and consumer (e.g., Yahoo). Archive site: used to preserve valuable electronic content threatened with extinction. Two examples are: Internet Archive, which since 1996 has preserved billions of old (and new) Web pages; and Google Groups, which in early 2005 was archiving over 845,000,000 messages posted to Usenet news/discussion groups.
  65. 65. Types of websitesBlog (or web log) site: sites generally used to post onlinediaries which may include discussion forums (e.g., blogger,Xanga).Corporate website: used to provide background informationabout a business, organization, or service.Commerce site or eCommerce site: for purchasing goods, suchas site: a site where persons with similar interestscommunicate with each other, usually by chat or messageboards, such as MySpace.Database site: a site whose main use is the search and displayof a specific databases content such as the Internet MovieDatabase or the Political Graveyard.Development site: a site whose purpose is to provideinformation and resources related to software development,Web design and the like.
  66. 66. Types of websitesTypes of websitesDownload site: strictly used for downloading electronic content,such as software, game demos or computer wallpaper.Employment site: allows employers to post job requirements fora position or positions and prospective employees to fill anapplication.Game site: a site that is itself a game or "playground" wheremany people come to play, such as MSN Games refers to domain names that are the same as thoseof geographic entities, such as cities and countries. Forexample, is the geodomain for Richmond,Virginia.Gripe site: a site devoted to the critique of a person, place,corporation, government, or institution.Humor site: satirizes, parodies or otherwise exists solely toamuse
  67. 67. Types of WebsiteInformation site: contains content that is intended to inform visitors,but not necessarily for commercial purposes, such, Free Internet Lexicon and Encyclopedia.Most government, educational and non-profit institutions have aninformational site.Java applet site: contains software to run over the Web as a Webapplication.Mirror (computing) site: A complete reproduction of a website.News site: similar to an information site, but dedicated to dispensingnews and commentary.Personal homepage: run by an individual or a small group (such asa family) that contains information or any content that the individualwishes to include.
  68. 68. Types of websitePhish site: a website created to fraudulently acquire sensitiveinformation, such as passwords and credit card details, bymasquerading as a trustworthy person or business (such as SocialSecurity Administration, PayPal) in an electronic communication.(see Phishing).Political site: A site on which people may voice political views.Pornography (porn) site: a site that shows pornographic images andvideos.Rating site: A site on which people can praise or disparage what isfeatured (e.g. site: A site on which people can post reviews for products orservices.Search engine site: a site that provides general information and isintended as a gateway or lookup for other sites. A pure example isGoogle, and the most widely known extended type is Yahoo!.
  69. 69. EmailAn E-mail Message According to Darwin Magazine: Prime Movers, the first e-mail message was sent in 1971 by an engineer named Ray Tomlinson. Prior to this, you could only send messages to users on a single machine. Tomlinsons breakthrough was the ability to send messages to other machines on the Internet, using the @ sign to designate the receiving machine.
  70. 70. EmailAn e-mail message has always been nothing more than a simple text message -- a piece of text sent to a recipient. In the beginning and even today, e-mail messages tend to be short pieces of text, although the ability to add attachments now makes many e-mail messages quite long. Even with attachments, however, e-mail messages continue to be text messages -- well see why when we get to the section on attachments.
  71. 71. EmailThe Real E-mail System For the vast majority of people right now, the real e-mail system consists of two different servers running on a server machine. One is called the SMTP server, where SMTP stands for Simple Mail Transfer Protocol. The SMTP server handles outgoing mail. The other is either a POP3 server or an IMAP server, both of which handle incoming mail. POP stands for Post Office Protocol, and IMAP stands for Internet Mail Access Protocol.
  72. 72. EmailA typical e-mail server looks like this:The SMTP server listens on well-known port number 25,POP3 listens on port 110 and IMAP uses port 143 (see HowWeb Servers Work for details on ports).
  73. 73. EmailThe SMTP ServerWhenever you send a piece of e-mail, your e-mail clientinteracts with the SMTP server to handle the sending. TheSMTP server on your host may have conversations withother SMTP servers to actually deliver the e-mail.
  74. 74. Email Email is very effective means of communication It is fast & asynchronous Email is quite often a source of spreading aviruses Email created new opportunities for marketing Cost remains same even if number of recipientsincrease
  75. 75. SPAMThe term "spam" is Internet slang that refers tounsolicited commercial email (UCE) or unsolicitedbulk email (UBE). Some people refer to this kind ofcommunication as junk email to equate it with thepaper junk mail that comes through the US Mail.Unsolicited email is email that you did not request;it most often contains advertisements for services orproducts. There are very few reputable marketersusing UCE to advertise goods and services.
  76. 76. SPAMThe most commonly seen spam includes thefollowing:· Phishing scams, a very popular anddangerous form of email fraud· Foreign bank scams or advance fee fraudschemes· Pyramid schemes, including multilevelmarketing (MLM)· Other "Get Rich Quick" or "Make MoneyFast" (MMF) schemes· Quack health products and remedies ….Cont
  77. 77. SPAM· Ads for pornographic web sites· Offers of software for collecting emailaddresses and sending UCE· Offers of bulk emailing services forsending UCE· Chain letters (for more information, see theKnowledge Base document What is electronicchain mail?)· Illegally pirated software ("Warez")
  78. 78. Searching on the Net Browsing on net is most popular application Search engines such as msn, Google ,Yahoo arefrequently used Many search engines used provide advancefeatures & use special syntax for helping the user Not surprising that advertising companies in thebusiness of website development always prefer toensure there site appears in top 10 websites
  79. 79. I.T. for Management End of Chapter 5