Networks (Part 1)

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

[email protected]

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