hi guys welcome back to CS classroom uh what I'm going to do today is I'm going to cover topic three of the IB computer science curriculum which focuses on networks uh this video is meant to help you either learn the topic if you slept during that portion of class or to review for your exam if you haven't seen this material in a while let's get started so the first thing that you need to know is that the idea of networks is kind of built on a server and client a server is a central piece of Hardware or a system so for example um if you are in a an airport for example Andre at a kiosk and you're trying to check into an airplane you're using a client and that client is sending information to a Central Computer in the network that's part of the airline that is a server so right here a client it's something that requests a service or connects to a server on the same network so it's a bit like a node or to something that's serving a central system and a server is a centralized system where all the data is held and where all the instructions come from or go to so probably just another good analogy would be like if you're in a restaurant right uh and or let's say you're in a bar for example you got your clients you're sitting around the bar ordering drinks you've got the bartender who's the server they share that centralized person who is handling your requests and that sort of server client concept is at the center of Networks now I'm going to post these slides in the description a link to these slides in the description and besides my explanations there's also helpful videos you can watch from other sources on YouTube in order to give you a better idea from a different perspective of how these Concepts work now a computer network is sort of taking this client server Paradigm and taking it to the digital world so we're talking about a computer network we're basically talking about multiple computers that are connected to each other and they can send and receive data from each other this may be to a centralized system as in our previous example or it might be peer-to-peer so just to each other but the point is a computer network is multiple computers that are hooked up and connected to each other now there are a couple of different ways to connect computer systems they're a hub a switch and a router now a hub is when a network device wants to send data to all devices on the network so for example if you have computers connected to a hub and one wants to send data to one computer I want to send data to another has no choice but to send that same piece of data to every computer on the network not very efficient next we've got is a switch which allows us to send data from one individual computer to another so if you've got six computers in a network you can send data from let's say computer a to computer B much more efficient then we've got a router and what a router does allows us to connect up con multiple networks to each other to kind of stitch multiple networks of computers to each other and create larger Networks a good example is a home network and the internet so the internet itself is a very large network but you can connect it to your own home like Wi-Fi network and access the internet through the use of a router which is serving as sort of a intermediary between those two things allowing them to talk to each other now the internet like I said the internet is really just a really large Network it uses something called the tcpip protocol to transmit data that means data all has to fit into a into a specific format and travel in a certain way as specified by the tcpip rules there's no centralized governing body there are some organizations that help the Internet run but there's a centralized body now there's an important distinction between the world wide web and the internet the internet is physical infrastructure that means wires that means uh mobile networks radio waves that allow different all the computers and the internet to communicate with each other the optional websites the google.com the facebook.com the the uh your blog all of those web pages make up the World Wide Web so the World Wide Web is the information and the internet is the physical infrastructure now isps run networks that provide internet access so an ISP allows you to connect into it and that ISP in turn gives you access to Internet exchanges these internet exchanges glue different isps together so the ISP is actually really just a really large Network and all those really large networks which are isps are glued together by internet exchanges and collectively these form the internet so these internet exchanges are usually run by academic institutions or non-profits they're they're really fundamental to how the internet works because they hook up your you know your Comcast and your CenturyLink and all that together and without them the internet as a whole as a Global Network couldn't really exist now the internet works by transmitting data in the form of packets so let's say you're sending a picture from this computer to this computer in like Zimbabwe to this computer in the United States that picture is probably going to get broken up into like 100 different packets and transmitted through the internet those packets maybe may take different routes through these different exchanges and different routers different isps until it gets to your destination they may travel separately but ultimately they will all arrive at the same destination and be put together to show you that picture now this method of transmitting information is called packet switching so a packet is again a unit of information multiple packets will make up whatever data you're being sent whatever data you're sending I mean they will be divided into your data will be divided into multiple Pockets they'll follow different routes and we'll get to the same destination as we showed below now these little boxes here are actually routers and they help those packets that are traveling get to their ultimate destination in the most efficient and quick way possible um in short they're sort of like relays on the internet that help packets get from one destination to another now this is roughly what a data packet looks like um there's a payload which is binary that's your photo or that's your text file or your movie or your text message or whatever you want to send you have a header which contains your the uh the sender and the destination then you're also going to have a footer which we'll look at later on or a trailer rather now again maybe you're sending a document from here to here it's going to pass through a series of routers so actually this this piece of data is going to be in one server and it's going to get sent to another server these might actually just be computers servers after all just computers but they're getting passed to a variety of routers getting they're getting broken up and passed to a number of routers until they get to your destination now again just to review a router is used to manage traffic control the flow of data packets and then send them to the right destination there's also an element of security involved with routers making sure that the those data packets aren't being sniffed out or aren't being intercepted by another person some videos you can watch now one of the um one of the big Concepts that it's covered is the different types of networks so basically a network is a collection of computers but these can have different configurations for different purposes the most common network is known as the local area network now this is something like what you'd have in your house so right here you've got this typical wireless home router um it's basically just it's basically just connecting different devices together and also assuming as interface between your network and the internet General local area network covers a single building with a radius of one kilometer or less so that's gonna be your house that could be a school Etc the next type of network is a wide area network which is basically the same thing as a local area network with the exception that it covers a much greater radius so it might be several local area networks stitched together using routers it could be a it could be different buildings connected through um through a network provider that have access to the same network now some examples of wide array network are the internet which covers the globe a cellular network which covers like a huge amount a huge area it could be like you know um a whole town or a whole deal I guess a village really or an ATM network which is just a network of multiple ATMs connected to a Central Banking computer over the an area of a city so same thing as local area network could be multiple local area networks stitched together but really fundamentally a wide area network is the same thing with a larger radius so again differences between local area network and white and wider your network geography is the biggest one local area networks will generally have a higher data transfer rate because they cover a shorter distance and so the signal isn't going to uh to be like I guess diluted is the way to say it um a set of costs are like so wider networks are generally going to be more expensive um just because of the amount of wire that you have to use and the amount of infrastructure you need to connect networks over a wider area and uh again partly because you have multiple devices you have multiple routers and you have multiple devices that are facilitating this connection you tend to have more technical problems with wands than lens so really like the differences again just come down to a function of distance now our next circuit network is a bit confusing it is a virtual local area network so basically what it is is this is going to be one or more physical local local area networks so you've got a local area network or maybe even a wide area network okay but when you look at this local area network this physical Network let's say you have two physical local area networks that are connected together instead because of the uh of the way the network has been set up it looks like it's five different Networks so virtual local area network is kind of is a network it's an artificial Network that is created by using network switches or maybe even using a software configuration and basically what it does is it mimics an actual physical local area network this basically allows you to have in terms of like when you look at a computer from a software perspective allows you to have more networks than you physically have and this is just so you could group different computers into these made up networks to these virtual networks um and give them different different access uh different security requirements to connect just give them different settings give them different configurations so in conclusion a virtual local area network is basically a made up a virtual Network that exists in order to divide uh groups of computers on physical Networks um based on security configuration or just whatever specific characteristics apply to those groups of computers so again right here we might have um right here we have three different physical local area networks they're connected by a switch but each color indicates a different virtual Network right so right here we have one that's connected to line a line B and Lon C and that determination is made by configuration by software rather than their physical architecture um so some of the similarities that are obviously used to connect devices and share resources but with virtual local area networks they're more flexible because let's say you want to like connect one take one computer and switch it from one network to another virtual with virtual local area networks you might just have to um like change a software configuration or do something in software maybe even just move a chord around on a switchboard versus with a local area network you might actually have to like just move that computer somewhere else and connect to a different router they're also safer because you can Implement different security settings for each vertical virtual local area network and an easier and more efficient way than with a physical lawn but they can be more complex to set up because again as we saw right here you generally need to hook up a virtual local area networks into separate areas on the switchboard or you'll need to do some custom software configuration to make this work but generally they're good for larger organizations because that means they don't need to have multiple uh local area networks instead they could have a fewer number of physical local area networks and just make up more virtual Networks so the next type of network we're going to cover is going to be a storage area network now what this is is purely a network of storage devices you've probably seen this if you've logged into your school network they appear as shared drives but they consist of multiple storage devices all hooked up together and basically you might have a storage area network and from the storage area network you connect you connect directly to any computers that want to access it you wouldn't even go through like a lawn or a Wi-Fi network in fact they're not accessible to your standard Lan so you won't be able to connect to a storage area network just by connecting to your Wi-Fi network uh they may store emails application data database data or just files and generally they'll have backup servers and backup battery so if there's an earthquake or something that Network can still say online and it can at least conserve its data they tend to have better performance for this reason and also given the fact that all of the servers are dedicated to storing data rather than doing other things like accepting uh website requests or whatever you do with a server so the point of storage area network is it is an efficient and fault tolerant way to access multiple storage devices [Music] this is kind of hard work you'd have multiple storage devices connected to a router or a switchboard and computers would directly have to access that storage area network okay so this is probably the type of network that you guys are most familiar with now this is basically a lawn but the devices are connected to the router using radio Ace Wireless Wi-Fi which is the just uh Wi-Fi just describes a type of radio wave um to Wi-Fi you can make requests to the router your Wi-Fi router which in turn makes requests to the Internet so that's how you get data back and forth off the internet through your router it's basically a lawn a local area network but just Wi-Fi now now one of the big advantages is that you don't really need to license the radio spectrum like you can just use it anywhere like you don't need to register your Wi-Fi router the same way you would a radio station there's no cable so you can move around there's Global standards so with your computer you can connect to a Wi-Fi network anywhere and it doesn't take much to set up a Wi-Fi network the disadvantages are interference like if you put a refrigerator right in front of your Wi-Fi router I mean you're probably not going to get very good a very good connection um limited range you can't use a Wi-Fi network outside of like I don't know like a probably like a 20 meter distance radius security um if you're like in your house someone could like drive up to your house and hack into your wireless network which they can't do with a wired connection because they'd have to like physically access your house and break in health concerns which like there's a lot of research on this I don't know how true this is but some people have health concerns with regards to wireless now the next step of network is a personal area network called a pen so this connects devices in a user's immediate area it's basically like a lan except it has a much uh smaller radius some examples include Wi-Fi hotspots and just Bluetooth devices so when you set up your you know when you allow your phone or your your airpods to connect to your laptop then that is technically a personal area network because you're connecting from one device to another one computer tune up really one computer to another uh using Bluetooth rather than Wi-Fi still a pen now here we've got the intranet and the Extranet so an intranet is like a private internet so you can't access it on the world wide web but you can access it if you're connected to the network that is hosting the Internet it's like a private internet it uses tcpip and there are web pages but it may it may only exist in a company so you might just go into your office building connect to the Wi-Fi network for your company not one that's internet enabled and then go to a specific address on the internet to see a discussion board just for those in your company so it's hidden from the Internet it's a private internet a great example is North Korea they have their own internet like they have this internet system but the Internet only consists are there their intranet rather than North Korean Internet only consists of servers and websites that exist on a network that is just like um enclosed in North Korea so people accessing the North Korean internet cannot access the World Wide Web they can't access Google Facebook they can only access other servers and by extension other web pages on this like isolated closed off Network an internet system can become an Extranet if it can be accessed to an online portal so you might have an internet system like just that you can only use when you're in your office when you connect to a specific Network in your office but there might be like a login page on your on your company website by which you can access pages that exist on the internet then it becomes an externet so in conclusion internet is a private internet that is closed off from the World Wide Web it only consists of web pages that are hosted on servers in a specific private Network that again is closed off from the internet these aren't really that common anymore but again it exists in North Korea it's still a concept right um so let's move on to a VPN or virtual private Network which is actually just a more common way of securely accessing servers information now you've probably used a VPN client like nordvpn or there's a lot of free vpns out there um if you download a VPN on your phone you're just getting a client that's accessing a VPN server that is hosted by the given company that owns the client that you download so for example if you downloaded the nordvpn app you're using that you are accessing the internet via a nordvpn server so basically what happens is if you look at we'll look at a diagram here um you as a user you download that app your VPN client you're sending information to a encrypted tunnel uh to a VPN server so let's say you want to go to google.com all right you are sending a request to google.com to the VPN server that request is heavily encrypted and that VPN server is then sending a request to google.com google.com is sending a response to the webpage to the VPN server and the VPN server is returning that to you through this heavily encrypted tunnel that exists between you and the VPN server so really you are sending requests and to the Internet so you're asking for stuff from the internet and getting information back to a VPN server and when you make those requests or when you send information online like maybe you want to buy something so you send your credit card number to Amazon that credit card number is going through is heavily encrypted it's being sent to the VPN server that VPN server is sending the credit card number to amazon.com amazon.com accepts it says yeah you bought it and sends a web page saying that okay you congratulations you bought that to the VPN server which then passes it to you the VPN server acts as an intermediary that means that when amazon.com gets your credit card number um it doesn't really know where your computer is or doesn't know what your IP address is and knows what your name is because you would have sent that information but all it sees is this VPN server this is acting as like sort of a barrier between between the user and between any and any website on the internet that you're accessing so it doesn't see the user it just sees the VPN server again like when you access Netflix when you want to access Netflix using a VPN for example Netflix will not see you as a user it's just going to see the requests coming from uh a server so from a VPN server so that's why for example if you're in Colombia you can access a VPN service based in the US and then Netflix thinks that you're in the US even though it has your your user login information it sees an IP address that's based in the US so going back um so that process of going to create creating and maintaining encrypted connection between the server and the client is called tunneling so right here we have a tunnel right here so we have a heavily encrypted connection between the user and the VPN server and that encryption that that process of encrypting and passing data through a passing encrypted data is called tunneling the encryption is done using Technologies like SSL TLS or ipsec which are all very secure Technologies um some of the advantages of VPN include authentication so no one can see what you're sending uh which well basically authentication means you have control over what information you sent and what encryption is used right so you have to log in to an app to be able to start using a VPN and to send information encryption which means that no one can can see what it is that you've sent tunneling which means data is heavily secured again that kind of relates to encryption but it's considered an advantage so data is heavily secured between you and the VPN and multiple exit nodes which basically means anonymity so when you when you're on the internet no website can really see exactly who you are or where you're coming from unless you explicitly give them like a username or some identifying information um the next network is called a peer-to-peer network if you like peer-to-peer networks are still used um I mean they're used for things like torrenting I would say they probably had their heyday well actually you know I guess technically cryptocurrency would be uh cryptocurrency would technically be considered a peer-to-peer Network as well um it's kind of getting into a different level of complexity but the point of a peer-to-peer network is that two computers are sharing Resources with each other not through some centralized server so for example like if you are sharing information on your school network for example um the information you send is going to go through some centralized server in the center so if you're sending it from this computer at this computer normally in a regular client server Network a usual Network it would get sent to some Central Point and then from there it gets sent to the other computer so everything is getting passed through some centralized point but in a peer-to-peer Network you can send things directly to other computers not to a centralized point so here in this peer-to-peer Network you have a connection with every other computer in the network and there's no centralized computer that all of your requests or all of your responses are going through each computer access both as a client and a server no centralization probably a great example of a peer-to-peer Network in in real life would be probably speed dating as opposed to like a dating website so when you get on a dating website you are putting information into a centralized repository which is a website and then people can look at that um like can take a look on the website and they can find you and they can send you a message to that website only right so any any communication you have with whoever it is you want to date goes to their website versus if you do something like speed dating you are not going through any anything else like you're just meeting individual people one at a time so there's no intermediary there's no Central system that your messages your communication is going through but you are just talking to those people on an individual basis so it's just peer-to-peer it's not through a centralized system so this is a normal client server model again think about our airport example we have multiple checking kiosks that information is going to a centralized computer and returning a response versus the peer-to-peer model everyone is communicating with everyone else there's no centralized server system it's basically a free-for-all now earlier we talked about protocols so protocols kind of are the rules for data transmission in a given Network all right so it's a comic actually does a great job of explaining networks but basically in the internet for example the protocol we use is tcpip this means that data needs to be in a certain way and is transmitted in a certain way on the internet and these are the rules that is transmitted that dictate that transmission https is used for transmitting data between a web browser and a server and SFTP is used for transferring data transferring files specifically from a client to a server so those are all examples of protocols that are used now protocols have a few basic Pro having a few basic functions or roles they are to maintain data Integrity to make sure the same data that is sent is received so for example if you send some data to Amazon like maybe your credit card number your name your address that data that you sent is the same that is received by Amazon flow control to make sure the data is sent and received at the same rate so when you're sending data between two computers like maybe even between you and Facebook like Facebook servers their Facebook's computers can receive data at a much faster rate than you can send it the flow control makes sure that the data that you send is received at the same rate on the other end so um and or I guess another case if you're like sending um if you're sending data if your computer can send data at a much faster rate than another computer can receive it on the network it'll force your computer to send it at a slower rate or it'll transmit that data at a slower rate on the next is to prevent deadlock so maybe you're receiving messages or you're receiving data from two different computers from the internet from another computer on your network it could be from anywhere deadlock makes sure that data doesn't collide with each other that two packets don't block each other that they can travel maybe maybe one packet um moves to your computer as is received by your computer and then the other packet goes and finally they're to make sure that there's no errors in the data is being transmitted so they make sure that similar to maintaining data Integrity they make sure that the data that is sent is the same data that is received and no errors are introduced in transit now while transmitting data um like just in data transmission generally transmitting data over the Internet there are seven layers to that transmission so they're basically seven late seven layers of processes that have to happen in order for data to be transmitted from one computer to another over a network um you have application presentation session transport network data link and physical now you can kind of see what role each of these plates like physical is the actual like wires or wireless connection an application is like the website that you're seeing like HTTP right now I'm not going to go too much into this just because you don't need to know what these layers do for the IB exam you just need to know the names of three of them so pick any three and just memorize them like physical data link Network application presentation session Um this can get really complex like I said for the IB exam just know three now the next topic we're going to cover is transmission media by transmission media we're talking about like physically what transmits our data packets so we're talking about that physical layer down here so Wireless uh ethernet uh fiber optic there are broadly two types of transmission media that's wired and Wireless now um in terms of wire we usually use ethernet which is also called a untwisted pair or twisted pair um and that's the one with like the square sort of input that you're probably used to using we have uh copper which is well actually that's also good probably gonna fall under copper because that involves copper wires but could also mean a coaxial cable which is what you use to plug in your TV to cable and then fiber optic fiber optic nowadays is used for long range like heavy duty network connections so for example if an internet company wants to transmit data to your net to your neighborhood they're going to have a fiber optic uh connection or like a a line of fiber optic that goes directly from their nearest data interchange or from their nearest facility to a junction box in your neighborhood and from there five and from there you're going to hook into the your internet connection in terms of Wireless we have radio waves microwave and wireless uh these are I mean these could be different but generally like we don't really use microwaves commonly like you and I are probably never going to use that really just talking about um Wireless so Wi-Fi now with transmission media there are four factors to consider security reliability cost and speed um now what would security any were talking about can someone hack it with reliability we're talking about how like are we going to lose data like how how reliable is the connection cost is how much does it cost basically in speed is how fast that connection now probably the two like most common connection transmission media are going to be Wi-Fi and ethernet this is kind of a breakdown like Wi-Fi has slower speeds than ethernet because you're transmitting through the air um versus ethernet you're just literally sending a signal to a piece of metal Wi-Fi is less reliable because you could have interference for example you could have physical objects um or like you you could have physical objects or geographical features blocking the connection um versus ethernet like that's not an issue right as long as that ethernet cord is well insulated and there's no magnets near there's no like uh electromagnetic interference uh Wi-Fi data needs to be encrypted because otherwise because people can access a Wi-Fi network who are who are near you like anyone who's new you can access the Wi-Fi network versus I would say that even even over ethernet data should be encrypted but it's a lot harder to like um to intercept your transmission because I physically need to plug an Ethernet like plug that cord into their computer and it's not it's a lot harder to hide that than to connect to than to connect to a wireless network um again latency just means ethernet is faster and deployment means Wi-Fi is easier you just really need to set up a Wi-Fi router versus with ethernet you need to have um like a router but then you also need to have a bunch of K ethernet cables that connect to all the computers that want to connect to your network um now broadly again we're talking we're going to compare fiber versus copper so Fiber Optic versus for example an ethernet cord because fiber optic is used again for transmitting more data at a faster rate over a longer distance probably because it has more bandwidth you can send more data over a given period of time it has you can send data over a much higher distance over a much longer distance rather and also it's not it's not susceptible to electromagnetic interference or voltage surges so it's not really like the data you send is not going to be susceptible to changes in the electrical Grid or I don't know like a magnet but right next to a cord because remember fiber optic is fiber is just a piece of glass and you're basically sending um you're basically transmitting light over a piece of glass so you're basically sending a signal it's kind of like a morse code where with a morse code you send sound like you just do like you just send patterns of sound uh the fiber optic you're sending patterns of light except at a extremely high frequency so for example you're having a light beep like probably like billions of time or millions of times a second or to transmit data um also fiber optic is more lightweight than copper or than a fiber optic cord so that makes it easier to transport um so generally fiber optic is better um but there's also some downsides so we'll get to those well okay we'll get to those right now actually so one of the downsides between fiber optic and ethernet is that fiber optic is more expensive it's actually the most expensive method but by which transmit data copter copper is the second most expensive and then Wi-Fi is the cheapest so one of the big advantages of Wi-Fi over any of these is cost one of the disadvantages of fiber is also cost and that's important to know also with fiber you need to actually like you can't have need to have a straight like a linear connection between two points you can't bend it the same way as you can copper because after all the fiber is a piece of glass so that needs to be taken into consideration as well um and Beyond cost yeah I would say that those those are two big disadvantages of fiber now here's we can look at some connection speeds right here um so this is untwisted pair copper cable we're basically talking about ethernet 100 megabits per second fiber optic is obviously way faster Wi-Fi varies varies so can be slower than ethernet but also faster and with uh and this is basically talking about line connections right here this is not that relevant but still interesting DSL internet connection this would be the speed fiber optic blows them all out of the water um 3G 4G which are just Cellular Connections now what we need to learn about having learned about uh transmission media is some factors that affect how fast data travels so the primary factor that affects uh transmission speed is traffic so how much data is being sent at a given point of time the more data that's being sent the more data that needs to basically you can have a traffic jam right so the slower your network speeds are going to be think about you know at 6 PM when everyone comes home and wants to watch Netflix that gets us to our secondary factors which are time of day distance uh data transmission is less effective usually over a distance and infrastructure and this infrastructure basically means that the quality and the way that uh that wiring is set up these will also affect transmission speed traffic is the most important factor followed by these factors and then we also might have environmental factors temperature interference Financial factors so the quality of equipment that might be used can affect the transmission speed so if you buy cheaper equipment you might have a less reliable connection additionally if you use Fiber Optic if you use copper over fiber optic you're going to have you know a much slower connection but fiber optics is going to cost you a lot more and the type of data so streaming data for example streaming Netflix is going to take up it's going to slow your connection down for others more than sending text files foreign this is kind of like a one-off uh so we use it kind of make it kind of connects into the other topics um just because compression is basically when you take data to make it smaller now compression can is often used to send data more quickly or to store more data in a set um side in a set hard drive or a hard drive with a set size you have two types of compression we have lossy and lossless compression so velocity compression actually removes data in order to make a file smaller so right here for example we remove some pixels to make this file smaller than the original we have smaller file sizes but it's irreversible because we're basically throwing some data away each time so mainly we're going to use lossy compression with videos images Etc so basically when we're doing compression you may have seen zip files or you know whatever that's an example of compression now the other type of compression is lossless compression so velocity's compression we use an algorithm to reduce file size so we're not really using we're not really losing data we're just kind of rearranging that data so our file size is going to be larger than lastly a lot with glossy but it's going to be smaller than the original and we use this when node data can be lost so imagine trying to compress an essay for example if you lose some of that data like your essay makes absolutely no sense at all that's a good use case for lossless so basically compression is when we're trying to make data smaller to send it or to store it and we have lossy and losses compression and you might have a question IB exam that asks whether you'd want to use lossless or lossy what are some of the advantages of lossy over lossless uh this is going to be our last section and it's going to be network security so network security we're basically talking about how to prevent unauthorized use of Networks now when we're talking about networks again remember we're talking about the internet so one of the big ways to prevent unauthorized use to networks or to websites or to networks of servers on the Internet is to use Authentication and we have three types of authentication we have one factor authentication which might just be typing in a password so you're utilizing something you should know in order to gain access to a network password pin whatever next way is two-factor two-factor Authentication so you're going to use you might have to type in a password and then have a text message sent to your phone on a pre-registered phone like a phone that's registered with that website and so this would be for example when you type in a password and then you type in you get a text message with a pin and then type that in on your website or like maybe you're trying to log into your Google account you have to tap yes on your Google account um and three factor is probably like the most secure maybe you type in a password you tap yes or you get a pin on your phone and you use um something that you have something that you have like it's part of your physical body right so one factor something you know two Factor something you know and something you have so using your smartphone in conjunction the password three factors something you know something you have and something you are so fingerprint facial recognition retina retina scan all of these are very difficult to fake because they are unique to you so three Factor authentication my bad pre-factor authentication type in a password get a text message or tap yes or no on your phone and uh and scan your thumb or press your thumb against um a thumb print reader on your phone or have your CI scanned or to show your face now another way of securing a network or data is encryption right so encryption is basically when data is encoded so you might use some standard like SSL or TLS in order to transmit data from one computer to another and the idea is that the data can only be read by a sender and a receiver and involves some sort of key a private key or a public key basically need to know what encryption is and that encryption can be used you don't really need to know how it works for the IB exam now the next is to control access to network using media access control or a MAC address so a MAC address is basically imprinted or assigned to every single Network enabled device so anything they can control to network through a network interface controller that has a MAC address so for example your phone has has a device or has a chip that can connect to a network that can connect to a Wi-Fi network that has a MAC address your laptop has a inter has a network interface controller that connects to Wi-Fi network that has a MAC address your computer has an Ethernet support that has a MAC address and this is this is imprint into every single device when it's made in the factory and it's Unique to that device so basically what you can do with the MAC address is you can only let's say you have a Wi-Fi network and you want to control access to that Wi-Fi network you can say that you only want certain devices with specific Mac addresses to be able to access that Network and that's called a whitelist so one method of Security is to create a white list of networks that are allowed to access uh your network and so when when a computer when any other device tries to access your network is strict against the whitelist if the MAC address of your device matches the whitelist then you can access it otherwise you can just to give you an idea this is an example of a MAC address it's six pairs of two hexadecimal hexadecimal digits another way to secure a network is a firewall firewall can be a device or a piece of software that analyzes data packets that are coming into your network um and based on what's In Those data packets it will either it can stop them or allow them to enter your network you can also analyze Mac addresses or IP addresses of incoming data packets like usually firewalls again will handle can handle that white listing procedure and aside from controlling incoming traffic incoming data packets it can also analyze and control outgoing traffic so outgoing data packets so maybe for example you want to disallow I don't know credit card numbers you want to disallow certain compute certain servers in your network from sending data outside of your network firewall would allow you to do that incoming and outgoing traffic the last one is like this one is is kind of hilarious because you'll actually get questions that involve this but it's like physical security so like this is the idea of having like locked doors around your router or a cage that no one can access or security guards or secure room or you might have your um like the area where you keep your network devices like your switches your routers your servers like um secured against hurricanes your earthquakes it might be EMP insulated so that like a magnet can't just be used to wipe everything on that Network or to disrupt the network so you might get asked questions of like how can the network be secured against unwant I guess unwanted or unauthorized users um or unauthorized people who are entering your facility without without authorization and like your answer may just be like have a lot like lock the door or have a cage or have security guards so keep in mind with some of the IB questions they're actually asking questions about how you can physically secure um different components of a network or data on a network so that's why that's actually the last slide um I think we covered that in about an hour but that is everything you need to know for topic three um now I would like to work through like actual IB questions I took a lot of information uh for the slideshow directly from the answers to IB questions but I'm not going to go over them just for uh copyright purposes um if you would like you can see them actually in the slides that are attached uh to this particular presentation with all of the answers attached one thing that I was unable to cover in a lot of detail was actually data packets um so if you look at the slideshow there will be a slide that explains data packets in detail partly because the best diagram I could possibly find for data packets and um what each part of the data packet does is from an IB question with the mark scheme so please make sure and take a look at that while you're going through this video or after you go through this video anyways I hope that was a value to you it's a really quick review I think you could use for the IB exam in conjunction with the slides in the description if you want to see more videos like this please remember to like And subscribe have a nice day