Networks (Part 1)

1. Networks (Part 1) What is a Network? Local Area Network Wide Area Network

2. What is a Network • A network is a group of computers linked together • Networks allow computers to share resources such as printers, disk space, files and databases • One would find networks in most companies and also now a days in most homes

3. Types of Networks • Networks come in different types, this effects the way the network works • The two main network types are • Local Area Networks – LANs • Wide Area Networks - WANs

4. Local Area Networks – LANs • A LAN is a network in which the computer systems are all located close to each other • A LAN is found in one building such as a school, a supermarket … • The distances between work stations is small so the connection is direct • The connection normally uses wire cables

5. Advantages of LANs Having a Network is a great advantage thanks to the capability of sharing resources but there are many more…

6. 1. Easier Communication • The first advantage of having a LAN would be easier communication • The work stations on the network computers can directly communicate with each other • Communication can be don • Using text  instant messaging • Using video web-cam)

7. 2. Device Sharing • The second advantage is device sharing • Peripheral devices such as printers, scanners, servers and so on can be easily shared with the many work stations • This saves a lot of expenses, as less hardware needs to be purchased • Modems can also be shared thus the Internet connection can be shared as well

8. 3. File Sharing • File Sharing is the third advantage of having a LAN • The file server would allow the sharing of different data resources • The users of different computers can update the same data, this keeps the data updated throughout the whole network ensuring consistency of data.

9. 4. Easier Administration • The fourth advantage is easier administration • The network administrator is the person in charge of all the access limitations of the network, software and hardware updates and so on • This way the network administrator can manage hardware resources and update any software from the main server.

10. 5. Expandable • The last advantage of LANs is that it is easy to expand the Network • This means that it would be very easy to add more working stations to the networks • The work stations only need a network card and a network point to connect a new terminal of the network

11. Disadvantages of LANs Apart from advantages there are also some disadvantages to having a LAN …

12. 1. Start up Cost • In order to implement and start up a LAN is cheap at all • The server and the cables are very costly • Some companies might not afford the expenses to start up a LAN

13. 2. Break Downs • A very common and big disadvantage would be break-downs of the whole network • If the file server breaks down, all the work station would not be able to access any files stored on the file server • This means no one will be able to print or use any other peripherals and software shared on the network

14. 3. Viruses • Viruses are a threat to all computers on the Internet (global network) • When a virus is found on a work station on the LAN it would spread very quickly to the other work stations on the network

15. 4. Security • Security is another disadvantage of LANs • Data security is important because many users are using the network • There has to be the proper data security to control hacking and unauthorized accessof certain data

16. Wide Area Networks - WANs • WAN stands for Wide Area Network • This time the network is found in a large areas that span in geographically area (different towns) • Wide area networks make use of a range of connection methods including satellites.

17. Uses of WANs WANS allow computers which are located in different geographic locations to communicate. This communication allows a number of services which enhance this type of communication.

18. 1. E-Mails

19. Electronic Mail • E-Mail is one of Internet’s communication methods • According to Darwin Magazine, the first e-mail was sent in 1971 • Ray Tomlinson created the ability to send e-mails to anyone connected to the Internet by using the now common e-mail address with the “@‟ symbol.

20. E-Mail Messages • An e-mail message is basically a text file • Thanks to technology we can now attach files and folders to our e-mails • e-mails save a lot of money spent on stamps and postage costs • e-mails also help the environment as less paper is used

21. E – Mail Addresses • Each e-mail address must be unique • An e-mail is made up of the; • The Username this is chosen by the user • The Domain part which is found after the ‘@’ symbol. This is the name of the host of the email service bertaborg@hotmail.com

22. Types of E-Mails • There are two main types of e-Mail: • E-Mail services which are accessed by a standalone applications such as Outlook • Free e-Mail services which are accessed through a web-site. Such as Yahoo!, Google, and Hotmail.

23. E-Mail Requirement • In order to send an e-mail an e-mail server is required • This e-mail server needs to have two services: • SMTP (simple mail transfer protocol) which is used to send e-mails. • POP3 (post office protocol 3) is used to receive e-mails.

24. Advantages of E-mails • Speed • Asynchronous: communication does not occur at the same time. One can reply/read emails at his/her convenience unlike real-time chatting • Cheap: many companies such as Yahoo!, GMail, Hotmail offer free e-mail services. • The same message can be sent to a large group of recipients. • Environmental Friendly

25. Disadvantages of E-mails • Not everyone has an e-mail address whereas by using normal post, everyone can be reached • Privacy: threat to privacy and security, if the password is known there will be total access to the e-mails and account data • SPAM: this is very common and very difficult to get rid of • Only Virtual Messages: no tangible products can be sent.

26. 2. WWW WWW stands for World Wide Web

27. The World Wide Web • WWW is a collection of web pages found on the Internet that contain in multimedia • A web page is a single documentof information displayed using colors, images and multimedia to look interesting • A web page may be too large to be displayed as a screen without scrolling.

28. Web Sites • Web pages are permanently available to any user of the Internet • Each organization and now a days even individuals that want to provide information to the public would organize their information as a web-site, consisting of many pages • Web sites are an effective way of putting information out there, they are used for advertisements, technical information, comments and ideas

29. Accessing Web Pages • Any web page can be accessed directly via the Internet if its full address is knows • If the address is not known users would need to use a search engine by entering a keyword to find many different web pages • Most web site have a home page (welcome page) which provides a starting point for a user to search the site which provides links to other related web pages

30. HTML • HTML stands for Hyper Text Mark – up Language • Web pages are usually prepared using HTML • But nowadays PHP or ASP are used in order to connect a website to a database and CSS is used for a much neater design.

31. Acronyms • PHP – Hyper Text Processor • ASP – Active Service Pages • CSS – Cascading Style Sheets

32. 3. Video Conferencing Video Conferencing allows communication to take place using web cams and microphones