topic 4 ICT

NIC stands for network interface card.

before a computer can be connected to a network it need to have a NIC. most computer have these when you buy them. 

it is a card containing ciruitry along with a socket. the socket allows the connection between the computer and the caling. the card is slotted into the motherboard so data can be transmitted along a wire 

a nic 

• prepareds data for sending over the network
• send the data
• controld the flow of data from the computer terminal to the transmission medium. 

Hub - A Hub is a simple device which is used to join comuters in a network so they are able to share files and a internet connection.

Switches - switches also join computers together in a network. however it only sends data to the computer it is need for, so it reduces the amount of data on the network and speeds it up.

Routers - routers are hardware device that joins several wired or wireless connections, it give internet connection. 

is a software that helps to look after the computers.

• makes sure computer have a up to data software.
• keeps hackers out
• check liciences for different softwares
• providing remote control 
• checking if user installed un licenced sofrware
• checking the speed of the processor.

data transfer media is the material through which data travels from one computer to another in a network 

the main types of data transfer media are

• metal wire

- high transmission speed

- Expensive

• fibre optic cable 

- Data travels fast

- small

- Expensive

• wireless 

1. the router is connected to the interent by a high speed broadband ceonnection

2. the router recieves data from the internet

3. it transmits the data as a radio signl using an anteni

4. the computers wireless adapter picks up the signal and turns the radio signal into data that the computer can understand

advantages                                                                disadvantages

- freedom of working anywhere                                    - power comsumption is high

- global                                                                        - security problems

- no cables needed.                                                    - limited range

for devices to communicate with each other in a network certain standards need to be used. standards are important because once device may send something to another in a form it does not understand. 

in order of a network tomrun properly certain procedures need to be used, without procedures 

• the securitty of a network may be compromised
• the network may run slowly
• fail lesisglations
• work may be lost
• actions may cost tge organisation time to sort out problems.

LANS 

• confined to a single bond
• ownership pf the communications - organsiation owns all hardware

WANS

• hardware is spread over wide geographical area
• third party telecommunocations equipment is used. e.g telephone and statelite
• 
  

this is a ring topology which is also peer to peer becuase there is no server.

with the ring topology 

• all computers are arranged in a circle 
• data sent by one computer passes round the ring until it reaches the correct computer

advantages

• easy to add extra devices
• each computer has the same access as the other so no one computer can hog the netowrk

Disadvantages

• if there is a break in the netowrk the whole network fails
• faults are difficult to locate
• it is impossibe to keep network running while devices are added.

with a bus topology, all the devices connected to the network are connected to a common shared cable called the backbone. signals are passed in wither direction along the backbone.

Advantages

• cost effective because of small amount of wire 
• easy to install
• easy to add extra devices

Disadvantages

• alot of computers can degrade the network
• if there is a break in the backbone the network cannot work

the star topology uses a central connection point to connect all the dives together. the central connection can be a hub, router of switch.

Advantages

• fault tolerant 
• load tolerant
• easy to add extr computers

Disadvantages

• higher cost 
• dependence on central hub

data sent using a mesh topology can take several different paths to it destination

Advantages

• fault tolerant - if one path fails another can be used
• easy to locate faults

Disadvantages

• higher cost - large amount of cables
• harder to maintain - long legnths of cables

peer to peer netwoks are where each network has the same status and they are able to communocate with each other. 

they are used for home networks, there is no cental management. and can access each others resources

Advantages

• cost saving - no server is needed
• no network manager is needed
• easy to set up
• no relianance on server
• lower operating cost
• peer responsibility

Disadvantages

• back ups cannot be made centrally
• pooerer  security
• some computers may run slowly

in clinet server netoworks  all computers are not the same status. usally a more powerful computer is used as a central computer, where all files are stored. called a server.the other computers on the network are caled client

Advantages

• security is better
• centralised data
• back ups are taken regularly
• faster access to programs
• centralised administration

Disadvantages

• 
  more expensive 
• need specialsit knowledge
• software is some sophisicatedand expensive 

the internet

the internet is a huge group of networks joined together. each of these consist of smaller networks the internet consist of hardw\are

world wide web

is a means of accessing information on the internet, the world wide web uses HTTP. which is one of the languages use of the internet to transmit information. www  makes  use of browser software to access webpage 

using the internet you have 

• email facilities 
• instant messaging
• peer to peer
• ftp

an intranet is a private network that uses the same technology as that used by the internet for the sending of messages around the network. the main use of an intranet is to share organisational resources and resources.

the main feature of an inreanet is that only emplyoyees of the organisation are able to use it. 

Extranets 

using an extranet custome, suppliers and other partners can access the information. extranets are not accessable by the general public and this is ensures by usernames and passwords. data can be sent via the internet or private commuication lines which offer more security

if internet is used the following security has to be used

• gateways
• firewalls
• encryption
• user authentication

• Ability to share files
• ability to share hardware resources
• Ability to share software
• lower software cost
• improves security
• easier to implement acceptable policies
• easier to back up fiels
• improved comminication
• central maintenacne support

• Technical Knowldge needed
• lack of access when file server fails
• cost 

communication software makes it possible for computers to send and recieve data over a network. when data is sent over a network the communication software manages the floe of data across the medium and also establishes certian rules. called the protocoo, by which computers can communicate. 

typical task performed by the communications software are

• collection the bits of data and putting them into packets before sending 
• adding information to ach package regarding which computer the data came from
• error checking
• establishing connection with remote computers
• chaning the packets into ordinary data 

the end