End of topic Revision

End of topic Revision

1. validation

   • What is validation?
     • validation checks if the data entered is reasonable
   • What is verifacation
     • Verifaication checks if the data if the data correct

2. Networks

   • What are the two main netwrks?
     • LAN and WAN
       • A LAN covers a small area such as one site or building, e.g. a school or a college.
       • A WAN covers a large geographical area. Most WANs are made from several LANs connected together.
         • A WAN covers a large geographical area. Most WANs are made from several LANs connected together.
         • The internet is a WAN.
         • Advantage of LAN and WAN are: 1) You can easily access files. 2) You only need to buy one licence 3) Easy to backup
       • Disadvantages of LAN and WAN 1) Cables are expensive 2) Viruses can affect all the computers 3) There is a danger of hacking,
   • Bus networks
     • Uses one cable
     • at each end of the cable is called terminators
     • everything is connected to one cable from the computers, peripherals and the server
     • Can become slw because of data trafficking
     • terminator is fitted to stop signals reflecting back down the bus.
     • Advantages and disadvantages of a bus network :
       • The advantages of a bus network are: it is easy to install it is cheap to install, as it doesn't require much cable
       • The disadvantages of a bus network are: if the main cable fails or gets damaged the whole network will fail as more workstations are connected the performance of the network will become slower because of data collisions every workstation on the network "sees" all of the data on the network – this is a security risk
   • ring network
     • In a ring network each device (workstation, server, printer) is connected to two other devices - this forms a ring for the signals to travel around.
     • Advantages and disadvantages of a ring network:
       • Advantage:This type of network can transfer data quickly
       • Disadvantage:main cable fails or any device is faulty, then the whole network will fail.
   • Star Network
     • In a star network each device on the network has its own cable that connects to a switch or hub. A hub sends every packet of data to every device, whereas a switch only sends a packet of data to the destination device.
     • The advantages of a star network are::it is very reliable – if one cable or device fails then all the others will continue to work it is high-performing as no data collisions can occur
     • The disadvantages of a star network are: it is expensive to install as this type of network uses the most cable (network cable is expensive) extra hardware is required (hubs or switches) which adds to cost if a hub or switch fails, all the devices connected to it will have no network connection < >

3. Secuerity

   • Antivirus software
     • There are a number of malicious software (‘malware’) programs that can cause damage to computers. These include viruses, worms, zombies, Trojan horses (Trojans) and Spybots.
   • Seccure password
     • firewall
     • When more than one person uses a network it is important to have user IDs and passwords. Only someone with a login and password can access that network. It also helps the network manager trace unusual activity to a specific user.
   • Firewall
     • A firewall is software that will block unexpected connections coming in to the network. Most operating systems include a firewall.
   • Encryption
     • The prefix for some web addresses is https instead of http. The ‘s’ indicates that it is a secure website and any payment or personal details that are inputted into the site will be encrypted.
   • Encryption
     • Any message sent over a network can be intercepted. Encryption is a method of changing the original numbers and characters so that they are hidden or disguised. This is important if you are sending sensitive information.

Images and files in the map