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Now you will learn a lot more by doing rather than just watching me talk about protocols and talk about
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things.
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So make sure that you download this packet tracer file and try this yourself.
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I'm going to walk you through a scenario and a few scenarios in this video and in subsequent videos
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and labs.
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But try this yourself you will learn far more by doing than by watching or listening.
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You learn to ride a bicycle by riding.
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You don't learn to ride a bicycle by watching someone else ride a bicycle or watching videos.
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So try this yourself.
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Okay.
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So in this example I've got a topology consisting of multiple devices so zooming out I've got a whole
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bunch of devices.
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But for this initial video we're going to concentrate on this P.C. which is in our internal network.
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In other words think of this as being at your home or company.
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And then we've got a device that's connected to the Internet here.
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So this would be our Internet reporter.
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What we're going to do however is connect to a server in our internal network.
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Now at home you may have multiple Internet connected devices.
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You could as an example simply open up a web browser on your P.C. and connect it to your Internet router.
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As an example if I open up a web browser and connect to an IP address in my network and don't worry
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too much about IP addresses at this point if you don't understand them.
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Basically an IP address is a number that you allocate to a device that allows it to communicate using
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a protocol which in this example is IP IP version 4 in this specific example here.
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I've got a Beatty home hub when you connect to Web sites such as Facebook dot com that is going to be
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using a protocol in this example HDP X which is an encrypted version of a GDP.
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A different protocol but that's kind of what it is.
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We encrypting HDP so you may have devices at home that you can connect to.
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We going to mimic that or represent that in Packet Tracer.
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So on the left here I have some servers running internally.
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I have a Internet router which is connecting me to the Internet as a further demonstration.
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I've got an iPhone.
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I could connect to that light.
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That's a cue like using Bluetooth and then do something to that light in your home you may have some
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devices that are connected via IP as well that light isn't using IP as in normal IP using Bluetooth.
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I'm connecting to that light via Bluetooth from my iPhone and turning it on and off but this light as
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an example is connected via IP so I can go on to my phone and then I could say OK let's turn that light
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off.
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So it's gone off.
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Turn it on now the way that works is I'm simply connecting to that light via TTP IP.
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You can actually look at the traffic on your home network using an application called wire shock.
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I'll talk about that in a separate video but in this example let's use Packet Tracer so that we can
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talk about the same protocols together.
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So on this P.C. I'm an open up a desktop and I'm going to open up a web browser now before I connect
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to a server I'm going to change the packet tracer mode to simulation mode so that we can see the actual
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packets going across the network.
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Now I need you to know some terms for the CCMA exam.
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It's basically how we referred to stuff if you like at the different layers.
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So when data is sent at the physical layer we sending zeros and ones across the physical layer that's
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known as butts.
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So the bits of data are represented on a fibre cable as light.
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So as a basic analogy if there's light it means a one.
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If there's no light it means a zero.
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So zero one would represent.
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That's why binary values on copper.
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Do we have electricity or not.
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So most fundamental example would be if there is electricity on a wire it means one if there is no electricity.
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It means a zero.
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So think of this as a light going on and a light going off is it on.
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Is it off.
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And that represents of.
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That's so it layer one we have bits on top of that we have frames.
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So at layer two we talk about a frame.
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So when we sending data through an Ethan it switch which is a so-called layer two device we are sending
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frames.
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So I'll use these terms.
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Frame is getting switched from one port on a switch to another.
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So when you hear the term frame remember layer two at least three we have what are called packets so
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a router which is a layer 3 device will rot packets from one interface to another and add layer four
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we have segments.
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So layer 1 is bits Layer two is frames Layer three is packets layer four segments and then at layer
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five to seven we have an application.
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Now let me warn you as I demonstrate these protocols it's going to take time because there's a lot of
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information you may find that it gets a bit boring if you do then do this yourself have a look at the
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protocols yourself and try and understand the messages but I'm going to spend quite a bit of time going
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through layer to layers really of four and the layer seven applications to try and help you understand
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what's going on.
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This kind of stuff is really important to understand.
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It's basic nitty gritty foundational stuff can be boring but it's important to understand you can't
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understand networking if you don't understand the stuff.
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So spend the time learning your protocols you will need to put in the effort and spend time learning
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your protocols if you really want to understand networking if you want to become an ethical hacker you
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need to understand the protocol so that you can hack them if you want to become a network engineer you
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need to understand the protocols to be able to configure network devices properly and troubleshoot network
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devices or troubleshoot network issues if you want to become an a good application developer you need
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to have an understanding of the underlying applications many nightmares are caused today for network
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engineers because of badly written applications application developers assume some of them who write
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bad applications that there's unlimited bandwidth there is no unlimited bandwidth if you write a per
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application it's going to make a network engineer's life very difficult as a lot of old network engineers
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will say it's always the networks fault and all the rubbish comes from the top and lands on our heads
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because people will blame the network even when there's an application that's at fault make sure that
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you spend your time learning your protocols so that you can prove it's not a network issue but it's
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an application issue.
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