Transcript Networks
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 Email 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 www.dolinski.co.uk 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 email 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 A baddy! 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 A Goody! 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?