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Published byWilfrid Butler Modified over 9 years ago
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Internet & E-mail Day 1
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Computer Networks Two or more computers can be connected together and it’s called as computer network. Computer Network: –Computers –Peripherals (Network Printers)
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Advantages of a Computer Network Resource Sharing –Data sharing –File sharing –Software Sharing –Hard disk capacity sharing Avoid data duplication Centralized databases Implementation of network software systems
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Classification of Computer Networks Local Area Networks (LAN) –Computer network spread in limited geographical area Eg. Department Network Class room Network Office Network Head Office Network Colombo City Network
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Classification of Computer Networks Wide Area Networks (WAN) –Wide spread computer network Eg. HSBC Network World Bank Network BBC Network DHL Network Air Line Reservation Network Internet
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WAN of WAN’s Six million computers ARPANet (Advanced Research Project Agency) to Internet Number of Services –World Wide Web –Email –Telemedicine –Video Conferences –Internet Relay Chat
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Internet Connection Dial-up Network Dedicated Line/ Leased Line ADSL ISDN VSAT
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Dial-up Network Internet Service Provider/ ISP MODEM Public Switch Telephone Network/ PSTN MODEM Computer
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MODEM MOdulation –Conversion of Analog signal to Digital signals –PSTN to Computer in user end DEModulation –Conversion of Digital signals to Analog signals –ISP to PSTN PSTN transfers analog signals
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Dedicated/ Leased Line Internet Service Provider/ ISP DSU Public Data Network/ PDN DSU Computer
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DSU/ Digital Service unit DSU converts unipolar digital signals to bipolar digital signals If transferring of unipolar digitals signal to long distance causes energy wasting and low signal levels PDN transfers bipolar digital signals to long distances
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Internet Service Providers/ ISP Provides internet connections to clients –Sri Lanka Tele Com –Lanka Internet –Dialog GSM –Lanka Bell –Eureka
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Creating Dial-up Network 1.Start button, Control Panel menu item 2.Internet Options, Connection tab, Setup button 3.Next, Connect to the Internet Option, Next 4.Setup my connection manually option, Next’ 5.Connect using a dial up modem, Next 6.ISP Name (Provided by ISP), Next 7.Phone number (Provided by ISP), Next 8.User name, password, confirm password, Next 9.Add shortcut on desktop, Finish button 10.Use shortcut and connect to internet
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After Connecting to the Internet Notification Area
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Web Browsers Application software which display web pages at client end Web pages written by Hyper Text Markup Language/ HTML Examples to web browsers –Internet Explorer (Microsoft) –Netscape Navigator (Netscape)
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Web Browser Client Web Server Static Web Pages Server Web Designing/ Static Web Pages
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Web Browser Client Web Server Static Web Pages CGI Programs Department Database Dynamic Web Pages Server Web Developing/ Dynamic Web Pages
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