Download Networks (Part 1)

Networks (Part 1)
What is a Network?
Local Area Network
Wide 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
Wide Area Networks - WANs
2.
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 messaging
2. 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 - 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.
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 user
2. 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.
2.
SMTP (simple mail transfer protocol)
which is used to send e-mails.
POP3 (post office protocol 3) is used to
receive e-mails.
Advantages of E-mails
1.
2.
3.
4.
5.
Speed
Asynchronous: communication does not
occur at the same time. One can reply/read
emails at his/her convenience unlike realtime 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
Disadvantages of E-mails
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.
1.
2. WWW
WWW 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 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
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
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.
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