Networks (Part 1)What is a Network?Local Area NetworkWide Area Network
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
Types of Networks Networks come in different types,
this effects the way the network works
The two main network types are 1. Local Area Networks – LANs 2. Wide Area Networks - WANs
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
Advantages of LANs Having a Network is a great advantage thanks to the capability of sharing resources but there are many more…
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 1. Using text instant messaging2. Using video web-cam)
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
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.
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.
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
Disadvantages of LANs Apart from advantages there are also some disadvantages to having a LAN …
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
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
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
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 access of certain data
Wide Area Networks - WANsWAN 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.
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.
1. E-Mails
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.
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
E – Mail Addresses Each e-mail address must be unique
An e-mail is made up of the;1. The Username this is chosen by the
user2. The Domain part which is found after
the ‘@’ symbol. This is the name of the host of the email service
Types of E-Mails There are two main types of e-
Mail:
1. E-Mail services which are accessed by a standalone applications such as Outlook
2. Free e-Mail services which are accessed through a web-site. Such as Yahoo!, Google, and Hotmail.
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:
1. SMTP (simple mail transfer protocol) which is used to send e-mails.
2. POP3 (post office protocol 3) is used to receive e-mails.
Advantages of E-mails 1. Speed2. Asynchronous: communication does
not occur at the same time. One can reply/read emails at his/her convenience unlike real-time chatting
3. Cheap: many companies such as Yahoo!, GMail, Hotmail offer free e-mail services.
4. The same message can be sent to a large group of recipients.
5. Environmental Friendly
Disadvantages of E-mails 1. Not everyone has an e-mail address
whereas by using normal post, everyone can be reached
2. Privacy: threat to privacy and security, if the password is known there will be total access to the e-mails and account data
3. SPAM: this is very common and very difficult to get rid of
4. Only Virtual Messages: no tangible products can be sent.
2. WWWWWW stands for World Wide Web
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 document of 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.
Web SitesWeb 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
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
HTMLHTML 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.
Acronyms PHP – Hyper Text Processor
ASP – Active Service Pages
CSS – Cascading Style Sheets
3. Video Conferencing Video Conferencing allows communication to take place using web cams and microphones