[Music] welcome to module 1.1 where we're going to talk about network components so we first have to begin by saying what is a network so network is a system of interconnected hardware devices used to connect in systems so that they can share resources and communicate with each other exchange information so the classic example of a network is the internet because it literally is a network of networks that are all interconnected together for the purposes of exchanging different kinds of data so the benefits of a communication network is obviously sharing resources so sharing things like files music streaming uh from one server to the client the reduced cost if everything is interconnected we don't have to have everybody in charge of everything they need to do business or to live life uh there's an ease of software installation and distribution so instead of passing around cds you could just grab something off the internet download it and install it improve security and communications flexibility in the workplace so that's where you get the ability to work from home someone keep instead of keeping your files on some centralized server in your business everything is stored on some sort of cloud provider so that you can just download it from there and use it wherever you need to there's a reduced cost of peripherals as more and more things go online and they're available on the network you can have cheaper and less powerful devices that are able to access those and then there's an element of centralized administration which is what we're going to focus on as far as the networking part of this and what you're going to see kind of come up especially in later modules in this course so uh the ability to do things once and it propagates out to everybody else on the network instead of having to go to individual computers over and over again and do those same things so communication networks contain three categories of components so you've got an end device or sometimes we hear it called a host you've got the intermediary or the interconnecting devices and then you've got the media that hooks it all together so here's some examples of what those things look like so the first category is the end device so you hear that called a host you hear it called a workstation you hear it call a node sometimes so that's just any device that's connected to a network and accesses some sort of information so that could even be a server that's serving up some sort of resource on the network it could be a workstation or a pc that's accessing the network a laptop a tablet a phone a printer scanner a camera system alarm systems entertainment devices even things that would fall more into the iot so like your nest thermostat or your computer connected alarm system your ring doorbell all those things are considered to be a host so they're on the network for a purpose all of these things have something called a nick or network interface card in them that is their way to be able to connect to the internet so it provides that internet connection so that can be something that's like a wired card that is plugged into a computer it can be integrated into the motherboard on a computer it can be a card that is plugged in that provides wireless or a little usb that provides wired or wireless they come in lots of different forms but at the end of the day they're the thing that connects into the host that allows it to have some sort of access on the network whether it be wired or wireless so they provide connectivity an interconnecting device provides connectivity to ensure that data can flow across the network between all these different end devices between the intermediaries through the hardware so they'll connect the individual hose to the network and it operates as a relay if you've got two or more systems then they all have to be able to talk to each other without the communications bumping into each other and getting lost so this is what helps us with that they connect multiple individual networks to form what's called an internet work so here's an example of some of those devices you've got a modem so that will convert an analog signal into a digital signal so that you can access the internet so if you have an isp that is heaven forbid dial up or you've got a cable you've got some sort of satellite no matter what you've got you've got some kind of modem that's going to take phone signals like with dsl or it's going to take some sort of analog signal maybe cable tv convert it into digital so your computer can read it and that's really what this is so you're either going to connect to an isp by dialing a telephone having heaven help you if you do so you have this dedicated call that's to the isp the entire time a digital subscriber line or your dsl so if you have maybe at t provides that verizon provides it i think as well you still use the telephone while connected and it's more high speed then you've got cable that's going to come through the coax cable that provides you your satellite service so the modem is going to act as a way to convert between an analog signal which is like the wave form to a digital that's ones and zeros ons and offs you've got a repeater so that is used to extend the range of a network so repeater is going to pass along traffic that it receives so that that traffic does not go a certain distance along the line which we'll talk about later and then degrade to the point that you can't see it anymore so it makes a single network reach longer distances a hub connects multiple hosts and devices so in the very beginning in the 80s when we first started networking things together we would hook up hubs and what a hub did is it would receive a port receive a signal on the port and then just repeat things out all the other ports you probably know some people like that they don't have any original thoughts right they just repeat everything they hear and that's what a hub is so we call a hub a dumb device so it doesn't really think it just repeats things back out so the step up from a hub is going to be a switch which we'll talk about in just a second so a bridge takes two separate networks two disparate networks and then enables them to communicate between each other so it's a bridge between two separate networks so it's got an incoming and an outgoing connection and those things are able to talk to each other and those can be wired or wireless so the switch is what we're going to see in our modern network topologies it connects together a number of end user devices which can be workstations printers scanners servers and it allows them to pass data directly but it's smart so a hub just repeats things back out but a switch actually stops and looks which port am i supposed to send this out of i'm just going to send the information to the intended recipient and not to everybody on the network so that makes it smart and a switch that interconnects end user devices is called a work group switch and that's what we're going to talk a lot about switches and routers as we get into networking here so another piece of this is a router so it's going to connect two or more either wired or wireless networks this is what the internet runs on the internet runs on routers so what a router does is it gathers information about all the networks that are connected to it and shares it with all the other routers on the network so that allows us to make really smart decisions about which network a packet is supposed to actually end up at um so that we can do something called path selection so we can pick the best way to get from point a to point b because on the network that's not necessarily a straight line it may be between lots of other routers so a router is going to make decisions it's a very very smart device it makes sure that only the intended recipient on another network gets the packet that's being sent and finally we've got a firewall so a firewall is the smartest and it's going to monitor incoming and outgoing traffic on a network it's going to look at relationships and going to determine if traffic if traffic is allowed or if it should be denied based on the content there's different kinds of firewalls and we'll have whole classes on firewalls later because they're so vital to network security but you've got a host based firewall and if you've got a windows operating system you've got a windows firewall that's built in and it is software that runs on that computer that's kind of monitoring what you're doing and if something is really obviously malicious then it's going to pop up and say i see this behavior coming and and i i know that following this pattern of ones and zeros this could be malicious then you've got a network firewall that's going to filter traffic from the internet to a lan and vice versa so it's going to look at the entire network not just the individual host there's different technologies of firewall so at first you just said if something's coming from this ip address and i know that it's malicious just block it and then we got into stateful packet inspection which just makes sure that says it makes sure the state of the connection is secure so it's not going to block something in the middle of a transmission even though the first few packets were allowed and then the third generation is looking at application layer protocols which we'll get more into later but just know like everything else in it that firewalls evolved uh from where they were to begin with and then the last piece of this is the network media so is it wired or is it wireless are we plugging it in with an ethernet cable or are we connecting it with a wireless network so most of the time on a modern network you have a combination of both you have some devices that it's more important for them to be wired so they'll be stable they don't move around very much like a desktop pc then you've got laptops that you want them to move around and be mobile so they will be wireless and then you've got things like thermostats that are connected connected to the network they could be either or so it just kind of depends but either way it's going to come down to isn't it work connected with wired or wireless media