Topic 8 - Networks

Network - A group of computers that are able to communicate with each other

Network Interface Card (NIC) - A NIC is a card containing circuitry along with a socket. The socket allows the connection between the computer and the cabling. It converts the data from the form in which it stored in, into a form that can be transmitted through the network media.

Hub - A hub is a device which is used to join computers in a network so that they are able to share files and an Internet connection

Switches - Switches are used to join multiple computers together in a network. They inspect packets of data and foward it to the computer that it is intended for

Routers - Routers are hardware devices that join several wired or wireless networks together (gateway to internet)

How Wi-Fi works

• The router is connected to the internet by a high-speed broadband connection
• The router recieves data from the Internet
• It transmits the data as a radio signal using an antenna
• The computer's wireless adapter picks up the signal and turns the radio signal into data that the comptuer can understand

Advantages of Wi-Fi

• Allows people to work anywhere a signal can be recieved
• Allows inexpensive LANs to be set up without cables

Disadvantages of Wi-Fi

• Can be health problems
• Power consumption is high - soon exhaust batteries and need to be charged again

Advantages of Stand Alone Computers

• Cheaper hardware and software - Wires, network cards needed to run a network are expensive
• Less IT knowledge needed -  More technical knowledge is needed to run a network
  
• Fewer problems with viruses - Viruses are less of a problem with stand alone computer as with a network, it may shut down the entire thing
• Not as hardware dependent - There is less dependence on hardware. With networks if the file server is down due to a problem, this affects the whole network.

Disadvantages of Stand Alone Computers

• Transfer of files between computers is sometimes necessary - Users often work on projects which means that they need to transfer data from one comptuer to another
• Hard to keep data up to date -  With a network only one set of data is produced, causing less confusion, but with stand alone two versions may be produced
• Hard to install and update software - Software has to be put on each computer
• Backups need to be kept by each user - Users need to take own backups of data

Advantages of Networks

• Ability to share files - No need to make copies of files as they can be accessed by all the computers in the network
• Ability to share hardware and software - No need to have a printer and other hardware for each computer, software can be shared meaning that everyone will be using the same version
• Improved security - It is easier for network managers to control the access from computers to the internet. It is easier to make sure that any material from the internet is checked with the virus checking software
• Easier to backup files - backups are perfomed by the network manager regularly
  

Disadvantages of Networks

• Technical knowledge needed - More IT knowledge is needed to run a network so specialist staff are usually needed
• Lack of access when server fails - If a server fails, the entire network may fail, which means that users might not be able to access files and data
• Cost - High initial cost of all the network equipment and training needed

LAN - A network where the linked hardware is confined to a single office or site and where all the wires and other devices needed for the LAN are owned by the organisation

WAN -  A network where the hardware is spread over a wide geographical area and where the organisation does not own some or all of the telecommunciations equipment used

Internet - The internet is a huge group of networks joined together (network of networks) enabling people to exchange and share data

Advantages of the Internet

• More methods of cheap communciation
• The ability to send and recieve files
• The ability to research information
• The ability to shop online around the world without leaving your computer

Disadvantages of the Internet

• Health Problems - Can lead to RSI, back ache and obesity
• Cyberbullying
• The ability to access inappropiate material - easy for children to access information/images by accident
• Children can form friendships with strangers - many paedophiles use chat rooms to talk to children

Intranet - Private internal network which allows employees of an organsiation to access information resoruces within the organisation

Extranet - Extranets are intranets that are opened to be accessed to select groups of users outside the company such as customers and suppliers. They use a username and password to access the the network

E-mail - An email is an electronic message sent from one communicatino device to another

Advantages of E-mail

• Vrirtually instantaneous - Mail is sent and recieved instantly
• No need for the formality of a letter - Supposed to be quick, direct and to the point
• E-mails can be accessed using a large number of devices
• Easily attach a copy of the sender's message with your reply - don't have to search for orginal message

Disadvantages of E-mail

• Not everyone has an e-mail account so ordinary post is still needed
• Junk mail is a problem and important emails may be sent to junk mail box which you may miss
• The system relies on people checking their email boxes regularly
• Emails, especially ones with attachments can contain viruses

FTP - File Transfer Protocol is a method of exchanging files over the internet.

FTP transfers files in a similar way to the way webpages are transferred from the file server to the user's web browser when the user is viewing information using the internet.

FTP transmits any type of file: Computer programs, text files, graphics by a process which collects the data into packages.

A package of data is sent and when recieved, the recieving system checks the package to make sure that no errors were introduced during transmission.

A message is then sent back to the system to let it know that the package is ok and that it is ready to recieve the next package of data.