CIE iGCSE ICT Networks



okay so networks and so network is basically and when you can't computerized devices together so they can share things and we'll talk about what they can share later on and the two questions you're often asked one is what devices would you need to connect computers or devices to a network and then the other one is what would you need to connect a network or devices to the Internet so the ones that you need to connect things together to form a network and the ones you can choose from a hub switch or network card so a hub allows you to connect all the computers together but safe computer a send something to computer D it would also send it to all the other computers connected to the network only the one that it's intended for then picks up that message so obviously you going to get a lot of data collisions because there's lots of messages being sent to places that they don't really need to be going so it tends to be with any network these days or any network of a certain size that a switch is used so this will forward the packets of data just to the correct computer so computer I would send it directly to computer D wouldn't go everywhere else and so a network card this goes inside the computer and it allows the computer to be connected to the network so this could be Wireless or it could be a wired network card so that's an example of what a hub looks like the computers plug in here with their network cables and then it goes into the network card and as I said it shares the data that way so this is a switch and often find there's a lot more ports on them because it's more intelligent it can send things to the right place and less data collisions and this is tends to be what what we use it's what we use in school this is a network card so if you look on the back of your computer or your laptop you'll see this port I would imagine and then this is inside your computer and it just plugs into the motherboard and and these can be wireless or wired network cards or both okay so the opposite that question is what do you need to connect to the internet so the usual answer is a router you've all probably got a router at home it sits on the atelier or imagine it's got score your BT written on the side of it and it stores information about the computers on the network it passes on the data packets to the correct computers like a switch so reduce these data collisions and it can of course connected the other thing you could write down is that you might need a modem and don't tend to have computers with modems in them as such anymore and but this would be a way of connecting to the internet using dial-up and you also obviously need an internet connection which is usually provided by your internet service provider so for example Tok Tok or sky or BT those are all ISPs these are what Reuters look like again you've probably seen these in your homes with your friends homes things like that so another device that you often need to know about it's a proxy server so it's essentially just a big computer and it acts as a buffer between the Internet and the network and so what this does is it passes a request to the Internet so someone will type in BBC Dakota at UK it passes out requests to the Internet it then gets the webpage and passes it back to the computer in doing that it means that it can monitor the internet usage of that person so they can check what you're going on you can block certain websites and it also has a firewall in there and which will monitor the traffic check no one's accessing the network that shouldn't be thank you so to even top to network local area network and wireless local area network and a local area network use these cables to transmit the data that makes it faster it also makes it more secure because if you're going to hack into the system or get into the system then you need to be plugging your cable in essentially which is obviously a lot more obvious than if you're using Wireless so this is a wireless local area network it uses wireless technology sounds daft but that gets a mark and it's normally less expensive and because there's less cabling you can easily add new devices so if you imagine one of our computer rooms at school we've got this your computers in here if we wanted to add another one in then have to run another cable through the ceiling into the server room we'll get in whereas if we bought a new laptop we just put it on the desk and connect wirelessly the transfer rates aren't as quick they're fairly quick but not quite as quick there are security issues because some egregious pieces are outside in a van and essentially all day trying to get into the network and there are interference issues things will interfere with the signals and the wireless signals so often that can be an issue so the reasons that we have a network then so as I said early we can share things so you could share resources such as printers files or the internet and you can communicate with other people on the network through instant messaging or emails and the reasons why you might not want a network is that you can spread viruses more easily if it gets to one computer and it's connected to all the others then obviously that can spread and if you're sharing the Internet out across a lot of people it can be slow so another thing that we'll talk about it's not essentially networks but I think it comes up in that chapter is video conferencing so if you're going to do video conferencing so it's a bit like FaceTime but a bit more businesslike see it have more people connecting all at the same time in a room with proper speakers and a big screen so to do that you're gonna need a webcam so that you can see each other speakers so you can hear each other in a microphone obviously so you can hear each other you need an internet connection of stable high-speed internet connection and obviously to do that you're going to need a router so advantage of this is that you can call meetings at late notice so yeah I'm going to get everyone into the office especially if it's a worldwide company and then there's no traveling so that reduces costs as well a disadvantage could be that your internet connection drops out or time zone differences across the world things like that and okay so authentication techniques and this is basically proving that you are who you say you are when you're using a computer system so it could be biometrics you might need to do a retina scan or thumbprint or a fingerprint scan before you're allowed access to the system you might have a swipe card or a smart card so you often see this in restaurants and things like that whether the the waitresses are accessing the till and they swipe their card it shows who they are also to – how much work they're doing but as well so that they can get into the tell system and the obvious one usernames and passwords disapproves you ha you are who you say you are so encryption this is a way of not stopping people getting your data but it's if they do get it it stops and reading it so what it does is imagine you're sending some information over the internet maybe via an email what it will do is it'll scramble or encode your message so it looks like gibberish and then the person at the other end has a key that decodes that information you don't need to know in depth how these keys are sent but just assume that they then have the key to decrypt it so if someone intercepts it halfway between you and the person you send it to it makes it unreadable they can't read it it's just code so therefore it protects sensitive data if it falls into the wrong hands so that's one method of protecting data as it's been transferred so from one place to another and in other ways that and obviously again have your IDs and passwords at both ends so that people can't log in and receive the data than when they shouldn't be firewalls we mentioned what this was earlier so this is a way of checking incoming and outgoing Internet traffic and seeing who's accessing the system what's been accessed and stopping things that don't meet certain security rules a digital certificate this is a way of saying that you know when using internet communication that you are who you say you are so it could be on a website that there's a digital certificate and you often see a little padlock come up if you're using a secure website if you click on that you should be able to see the digital certificate and it can also be used in emails as well and then finally and make sure that both parties have anti-spyware so that um spyware software essentially can't be this installed on either computer which will then spy on what's going on it will record things it could be a key logger it could be just seeing what websites are being visited things like that so have an anti-spyware will stop any of that malicious software being installed so finally internet versus intranet and the internet is obviously global the intranet is in a website a site set up within an organization so the internet is public anyone can access it whereas the internet intranet sorry is private you need to be within that organization to access it and therefore the data on the intranet is usually reliable because it's set up by that company for their employers employees sorry so it's likely to be genuine information whereas on the internet anyone can post anything so it tends to sometimes not be a quite as reliable but the internet does have more information because it's global than an intranet does they all sound fairly obvious I know but they're deeply bookmarks so that was a quick introduction to networks and you're going to need to know more detail don't just rely on this video

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