Chapter 3

 The characteristics and purpose of: ◦ Intranets ◦ Internet ◦ Extranets

 In the last lesson we looked at different types of networks in terms of geographical location. ◦ LANs ◦ WANs ◦ Virtual Networks  Now we will look at what methods we can use across these types of network to access data and services.

 Commonly mistaken for the World Wide Web.  The Internet is the infrastructure that the World Wide Web can run on.  The internet comprises of telecommunication devices that connect computers together: ◦ Telephone lines ◦ Cables ◦ Mobile phones ◦ Satellites ◦ etc

 The World Wide Web comprises of hypertext documents which connect together.  They can contain sound, images, text, movies and animation.

 Because you can connect to the internet with any device that has an external communication link...  The internet is often called an Open Network.  It uses TCP/IP communication between devices. ◦ TCP: Transmission Control Protocol ◦ IP: Internet Protocol

 The internet provides users with a number of services including: ◦ World Wide Web ◦ ◦ File Transfer ◦ Internet Relay Chat (instant messaging) ◦ Playing games

 Many of the services on the net can be accessed via web browsers.  However, sometimes you need specialist software to access some of the other services.  For instance...to upload this content to I need to use an FTP program. ◦ FTP: File Transfer Protocol.

 The image below shows a file being updated from my PC to my website via an FTP application.

 This provides the same services as the internet but on a closed network.  Many companies use the same technology that the internet uses to transfer files across departments.  An intranet can run on a LAN or across a virtual network using a WAN.

 Similar to that of the internet only that it provides: ◦ Internal ◦ Internal web Pages ◦ Internal chat ◦ File transfer ◦ Gaming (if you are allowed!!)

 Many companies, such as schools, put important company documents on their intranets.  This has allowed companies to cut down on paper costs.  Security is also improved as important documents can be transferred safely within the network. I can’t see what’s being transferred! Intranet Server

 This is basically an intranet that allows outside access!  A user will need an internet connection to connect to the intranet.  To gain access they will need to provide some security information such as username and password. WOOT! I have access! Intranet Server

 These provide employees a little more flexibility and allows them to work from home in some cases.  Files can be kept confidential but there is still some risk that the network could be hacked as it does allow connections from the internet.

 Study the table on page 73 and 74 of the text book which summaries the characteristics and the purposes of the internet, intranets and extranets.  Once you have looked at the table, close the book and see how many you can write down without looking.  If you can remember at least 3 characteristics and 3 purposes for each one you are well on your way to remembering all of them!!

 Bonus History Points! ◦ Can you find out the original purpose of the internet? Where did it come from and why was it made?