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Let's talk about sub netting so sub netting is important in networking you hear about it all the time

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you hear even people perhaps freaking out.

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I know I freaked out when I heard that I had to do it for exams like network plus or CCMA and I feel

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like there are a lot of complicated methods out there for submitting but there was a method that was

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shown to me middle of my career and it just blew my mind.

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It's really really fast submitting method and I really want to break down for you what sub meeting is

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why we do it and then show you the methodology behind it.

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So if we want to talk about submitting if we just come in here and just do an eye f config and we look

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at our IP address right we have our eye net which is our IP V4 and you can see here too we have this

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net mask.

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This is also known as a subnet mask or a subnet and it just says 2 5 5 5 5 2 5 5 0 doesn't really tell

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us a lot if we don't know much about it but this is what a subnet looks like.

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And we can think of subnets in ones and zeros it's all bits.

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Right.

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So we've got eight bits here.

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Just like an IP address IP before same thing.

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Eight bits eight bits eight bits and another eight bits and we've got ones and zeros if all the ones

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are switched on we've got two hundred and fifty five.

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If none of the ones are switched on we've got zero.

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And depending on how those ones and zeros are switched on or off determines a lot of things for us and

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that's why this net mass is important now.

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Attached to your resources for this course I've created an excel sheet that I think will be useful.

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So we look at the Excel sheet here is the cyber mentors submitting sheet and let's talk through this.

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It looks like a bunch of numbers and it might look crazy for you.

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And we're going to talk about how this breaks down how the bits break down and then how I would write

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this shorthanded for an exam or a test or do something that I do on a day to day basis.

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So first let's talk about the bit so come to the bits tab here and we have our 8 bits right wing countless

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across and there's eight here on the count and you can see that and it starts with 128 and descends

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down to one you just keep cutting it in half right.

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So 128 64 32 sixteen eight whatever.

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What's more important is why we get to these numbers.

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So if we have a one switched on here it adds to the value when all the ones are switched on it equals

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to 255.

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You see all the ones switched on here if we were to highlight overall this come down to the sun you

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see the sun is two fifty five.

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That's all this formula is doing here.

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So if we were to come through and you see all the zeros here nothing's flipped on to actually turn any

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value on here.

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How this actually works is the switch has to be on in order.

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Right.

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So if we were to switch on another bit we'd have to switch it on here and we'd have to switch another

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one on here.

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We could just come down here and switch it on here.

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It wouldn't make sense it doesn't work that way.

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Not with subnet.

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So we're going to take these back off and show zeros again.

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But you see how the values change if for example we had this network and you saw the default and I'm

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showing you the 2 5 5 2 5 5 2 5 5 0 this standard here because that is what's known as a slash 24 network.

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That's very very common and it's very common because it's used mostly in households and small businesses.

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And it's done this way because of the amount of hosts that it allows.

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Now if we talk about the host you can see that I have here two to the eight power why do I have that.

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Well we actually go by how many bits are switched off our how many hosts are available to us.

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So if a hosts here are a bit was switched on then we lose the amount of hosts we have available to us

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and the subnet gets smaller and smaller.

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Now don't worry too much about the ones and zeros.

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It's gonna make a lot more sense when we stop talking in these binary terms.

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I just kind of want to break down the math behind it first before we make it really really simplistic.

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So again we've we're talking about what's called this slash twenty four whack twenty four network and

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it's so standard because of the host.

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Again 256.

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Think of all the devices in your house you have cell phones you probably have computers you might have

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like a Roku or Amazon Fire or something along those lines you may have smart TV's or smart watches or

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something that connects to the Internet.

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Well again they're all connecting through net right and going out but the amount of hosts that you can

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have on your private network really depends on the subnet mask and how you set it.

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So we have this class C that you saw before the 1 9 2 1 6 8 dot 1 or dot 0 or however you want to have

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it.

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Right.

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Well it allows us to have two hundred and fifty six when we have a subset of slash 24.

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So that's very common for a household it's also common for a small business maybe there's a printer

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some few devices in there but they're never gonna get over this two hundred and fifty six hosts.

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OK.

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So when we come to the subnet cheat sheet let's break this down a little bit differently.

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So we have our hosts here.

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Let's start with the slash 24 we just were.

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And you saw that there is 256 available hosts as we start turning off bits OK.

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We turn off a bit here we turn off a bit.

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Keep going down the list.

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The host start getting bigger and that just corresponds.

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Here we have a slash 24.

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And the only reason I'm saying twenty four is I'm counting the ones across.

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Right.

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So we've got 24 bits switched on.

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If we had twenty three OK.

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It gets bigger and bigger and bigger.

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Now let's stay away from the ones and zeros.

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I think it's a little bit complicated.

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The better way to think about this is to look at the subnet mask down here and I'm going to replicate

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this.

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And then we're going to come back to it.

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So what I do here is we can have a possibility of 32 bits switched on.

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Right.

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So I'm just making a new tab and I'm just gonna go over here and I'm going to hit control and drag this

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across till it hits eight OK.

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And then I'm gonna do the same thing with nine on the drag and across all I'm doing is just making really

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quickly 30 to place holders and I'm just emulating here.

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If we had the possibility of thirty two different switched on bids.

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So imagine one bit of switched on.

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Imagine all 32 bits are switched on.

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That's the possibilities here.

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Right.

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So always for sure we're going to have an amount of host and we're gonna have a subnet mask.

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OK.

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So we'll just call it subnet their we always start here with 128.

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Just like the bits that you saw.

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You saw the 128 start in the bits.

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Let's just start also with 128.

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Now as you saw every bit that switched on.

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Remember when we switch a bit on over here it starts decreasing.

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So we're gonna decrease for the bits that are switched on.

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Sixty four thirty two 16 8 4 2 1.

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You come over here and when I like to actually do is I like to just add these numbers together and you

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could see one twenty and sixty four is one ninety two and then you can add these two together so you

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get one ninety two thirty two you just add diagonally is the way I've I actually always do it.

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So two twenty four to forty to forty eight to fifty two to fifty four and two fifty five.

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Now what does that correspond to.

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It corresponds to the possibilities of the bits being flipped on right.

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So this looks just like what you see here.

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Same deal.

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And if you had a one underneath of it.

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OK.

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Then you got 128 if you've got another one underneath of it.

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Well guess what.

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You've got one twenty eight plus sixty four which is one ninety two and this number keeps growing.

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Why is this important.

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This is still all ones and zeros right.

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Well let's start thinking about it.

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If we have a slash twenty four network we've got twenty four bits turn on our subnet mask is 2 5 5 2

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5 5 2 5 5 0.

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If we had a slash 16 it becomes 2 5 5 2 5 5 that 0 0.

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Why.

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Where are these changes coming from.

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Let me show you this.

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OK for a slash a.

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I'm just tying this into just this right here.

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Well this is coming from the number of bits that are turned on eight bits turned on.

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We've got 2 5 5 and the rest are zeros.

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You got another eight bits turned on 2 5 5 2 5 5.

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The rest are zeros come down to this slash twenty four which is that really common subnet that you see

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and you've got 2 5 5 2 5 5 2 5 5 0.

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Now this is very common.

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OK.

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And let's go back to the cheat sheet now and you could see that I've got X as a place holder in the

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subnet.

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So what I'm saying here is you look at this list and you say I've got a slash one well for this whole

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area here from one to eight the place holder is going to hold in place of this X..

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So for a slash one if I've got one 28 then guess what it's going to become 1 28 0 0 0 because that's

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how it would be if you turned on just one bit here and made all of these zeros.

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Guess what.

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Just the 128 would be on the rest would be zeros.

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OK.

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If we had a slash 14.

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OK.

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So two five fives automatically flipped on you have a slash eight already you pass through it.

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OK.

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So you're starting on the second iteration here slash 14 corresponds down here to 252.

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So you'd have a 2 5 5 2 5 2 0 0.

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So all this is is place holders let's go back to the sheet here.

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So I make this quick and dirty list.

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This is what I write out when I'm just writing out something quick for an exam.

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All right out one thirty two I'll put the host here and I'll put the subnet here.

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So again if we know that once we cross through eight 16 24 32 that has a two five five in front of it

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all we've got to do then is we'll say slash twenty seven.

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Well we've come through three columns then I know for sure that we've got 255 255 255 got something

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right.

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You see the slash twenty seven.

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You come down here.

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The subnet would be to twenty four say 28.

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OK.

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2 5 5 2 5 5 2 5 5.

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Look at the 28.

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You've got a dot 240 and this is going to be confusing.

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This is subnet it is not necessarily easy once you get the chart down it makes a lot more sense.

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So let's start piecing some more things together.

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When I say that I've got host now the host I'm showing you only correspond to these first two rows but

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it's very common or very useful just to know this number right off the bat.

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Now if you look at the cheat sheet what you can do here is you just know that you start with a one or

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you start with the 128.

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You go down but every time you go up your doubling and why are we doubling do remember from the bits

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part every time a bit is turned off.

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So as we go up a number we take it to the next power.

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So we've got ape it's turned off.

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We take two to eight power.

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It's 256.

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Well here you go.

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Look come through here.

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Two fifty six.

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We go to the ninth power 512 to the tenth power.

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Ten twenty four.

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It just keeps doubling.

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OK.

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That's all you've got to think about in your mind is he keeps doubling.

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So on an exam for example you might have something like what.

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How many host could be potentially in a slash 20 network.

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And you come to your cheat sheet that you made or you have in your head and you say well four hundred

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ninety six and then we'll get to this in a minute but we have to subtract two.

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So four ninety four potential.

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And why is this all important.

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Why do we even care about any of this.

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Why am I rambling on.

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Well you need to know based on the network.

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OK.

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The slash twenty four is great for a small office home network.

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However you want to have it.

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But what if you're a large enterprise.

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Maybe you have thousands of devices.

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OK maybe you want to slash 16 network.

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That might make more sense for you or you even see some with a slash 8 network.

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It just depends on how big the company is the larger the company the greater chance that you're going

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to see that they're not using slash 24.

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Or they could even have submitted segments of their network where say they have just telephones and

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they've got five hundred employees and five hundred telephones.

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They might just have one slash twenty three network for nothing but telephones because that's the amount

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of hosts that fit in there.

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So what we're after with submitting is how many hosts can we fit and what is the mask that's behind

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it.

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So those are questions you might be asked in exam.

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And these are questions that you're just going to see and when you're given addresses see you're doing

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a pen test for a client.

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You might be given something like this.

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You might be given IP address 1 9 2 1 6 8 1 0 0 slash 24.

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OK.

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And immediately in your head you're like oh slash 20 for that standard.

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There could be up to two hundred and fifty six hosts or 250 for hosts or devices in this network.

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But if they gave you something like 1 9 2 1 6 8 1 8 0 0 slash 20 then you might look at your little

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chart and say four thousand ninety four hosts.

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Remember when you subtract two four thousand ninety four hosts in this network.

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Now I know if I'm scanning this I'm up against a lot more devices potentially than I am in this.

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OK.

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So when a client gives you your subnets they might just write it out like this.

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And depending how big your client is might depend on how big their subnets are for you.

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For example I just pen tested a client that was a slash 16 all the way across and it looks something

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like 10 dot 1 0 0 slash 16.

234
00:14:07,250 --> 00:14:07,670
OK.

235
00:14:07,670 --> 00:14:13,220
And your subnet mask for that would be something like 2 5 5 2 5 5 0 0.

236
00:14:13,250 --> 00:14:14,840
And how does this come into play.

237
00:14:15,170 --> 00:14:19,610
Well every time you have a two 5 five that number is locked in place.

238
00:14:19,610 --> 00:14:21,080
That's another way to think about this.

239
00:14:21,350 --> 00:14:23,680
So that 10 is always locked down.

240
00:14:23,690 --> 00:14:30,050
This one is always locked down the rest of the bits are fair game meaning we could have 10 dot 1 dot

241
00:14:30,050 --> 00:14:38,150
1 0 dot one die two to three we could actually have a zero here zero not one got to the three to four

242
00:14:38,390 --> 00:14:47,030
and that's how this number like a slash 16 gets so big because you have ten got one dot zero zero through

243
00:14:47,030 --> 00:14:51,860
two hundred fifty five on the possibilities which equals two hundred and fifty six hosts.

244
00:14:51,920 --> 00:14:55,000
Ok for one range you get 256.

245
00:14:55,010 --> 00:15:00,440
Well imagine you have to do that two hundred and fifty five other times.

246
00:15:00,440 --> 00:15:01,190
Right.

247
00:15:01,220 --> 00:15:04,810
And that number gets substantially bigger here.

248
00:15:05,030 --> 00:15:09,240
And then if you were to have a slash eight then of course it gets bigger and bigger.

249
00:15:09,260 --> 00:15:13,040
So what you need to realize are a few things here.

250
00:15:13,190 --> 00:15:16,610
We have these addresses and you see the slash ones.

251
00:15:16,600 --> 00:15:20,270
I say again we call them wax whack 24 is going to be very common.

252
00:15:20,300 --> 00:15:26,150
I would say whack 16 is probably your next common you might see some weird sub minted networks like

253
00:15:26,150 --> 00:15:28,160
this subnet networks like this.

254
00:15:28,160 --> 00:15:31,190
But typically it's slash 24 slash 16.

255
00:15:31,190 --> 00:15:38,000
Now your network I.D. is typically what is known as your first address and your broadcast diary I.D.

256
00:15:38,000 --> 00:15:39,530
is known as your last address.

257
00:15:39,530 --> 00:15:43,040
This is not always the case but it is very common.

258
00:15:43,070 --> 00:15:46,190
And let me log back into this Kallie machine here and I'll show you.

259
00:15:47,090 --> 00:15:53,590
So we have our IP address 1 9 2 1 6 8 fifty seven dot one thirty nine.

260
00:15:53,990 --> 00:15:58,350
And we've got a net mask of 255 255 255 0.

261
00:15:58,400 --> 00:16:03,170
What does that tell you from what we just learn that tells you we have a slash 24 network.

262
00:16:03,260 --> 00:16:03,590
OK.

263
00:16:03,590 --> 00:16:04,960
This is a common network.

264
00:16:05,000 --> 00:16:08,450
There are potentially two hundred and fifty four hosts.

265
00:16:08,450 --> 00:16:09,450
Why do I keep saying.

266
00:16:09,470 --> 00:16:10,970
Why do I keep subtracting two.

267
00:16:10,970 --> 00:16:16,250
Well we've got a network I.D. and a broadcast I.D. or broadcast IP here.

268
00:16:16,250 --> 00:16:20,510
Well what we need to know is we are dot one thirty nine.

269
00:16:20,510 --> 00:16:25,160
We could be anywhere from one to dot 254 within this network.

270
00:16:25,160 --> 00:16:27,070
That's our two hundred and fifty four possibilities.

271
00:16:27,080 --> 00:16:33,500
This zero means we have the flexibility to be any IP address range from one to two hundred and fifty

272
00:16:33,630 --> 00:16:39,810
war usually usually a dot 0 for this IP here in a dot two fifty five.

273
00:16:39,810 --> 00:16:44,190
Make up your network I.D. and your broadcast IP.

274
00:16:44,640 --> 00:16:51,630
OK usually so if we were to say something along the lines of let's go back to this Excel document and

275
00:16:51,630 --> 00:16:57,840
we were to say something along the lines of this let's say that we have a slash 24 network and we want

276
00:16:57,840 --> 00:17:07,200
to know how many host We want to know how what our network ideas and what our broadcast ideas for IP

277
00:17:07,200 --> 00:17:07,380
is.

278
00:17:07,410 --> 00:17:08,430
OK.

279
00:17:08,610 --> 00:17:11,790
We would say OK and we'll we'll get it one more.

280
00:17:11,790 --> 00:17:13,640
We'll say it's a slash 24.

281
00:17:13,980 --> 00:17:21,820
And the IP starts with 1 9 2 1 6 8 dot one dot zero.

282
00:17:22,370 --> 00:17:22,970
OK.

283
00:17:23,010 --> 00:17:24,460
Or we can even write it like this.

284
00:17:24,460 --> 00:17:28,090
1 2 1 6 a 1.0 slash 24.

285
00:17:28,200 --> 00:17:32,900
Delete this and we'll say what's our subnet mask.

286
00:17:33,750 --> 00:17:36,590
What's our host what's our network what's our broadcast.

287
00:17:36,600 --> 00:17:40,490
So subnet you come to your cheat sheet you say OK slash twenty four.

288
00:17:40,620 --> 00:17:46,930
I already know that I need to be filling in this area here on the X so I'm just in come in 255 255.

289
00:17:46,950 --> 00:17:48,210
What's the x.

290
00:17:48,210 --> 00:17:52,330
Well we know to come down this row to fifty five here.

291
00:17:52,350 --> 00:17:52,980
God zero.

292
00:17:53,920 --> 00:17:54,520
Okay.

293
00:17:54,540 --> 00:17:57,090
And then we've got host somebody can expand this a little bit.

294
00:17:57,600 --> 00:17:59,070
We've got the hosts OK.

295
00:17:59,120 --> 00:18:05,880
Hosts are right here 256 hosts potentially 254 though because we always subtract two from the hosts

296
00:18:05,880 --> 00:18:06,690
total.

297
00:18:06,690 --> 00:18:13,430
So our network I.D. is usually the first address available to us which is 1 9 2 1 6 8 1 0.

298
00:18:13,560 --> 00:18:22,390
The broadcast is 1 9 2 1 6 8 1 255 meaning available to us is anything from DOT 1 2 dot 254.

299
00:18:23,430 --> 00:18:24,710
Let's take a look at something else.

300
00:18:24,720 --> 00:18:26,840
That's a basic example.

301
00:18:26,850 --> 00:18:28,660
Let's do like a slash 28.

302
00:18:29,100 --> 00:18:32,140
Let's say we got 1 9 2 1 6 8 1.

303
00:18:32,160 --> 00:18:35,320
Got zero slash 28.

304
00:18:35,370 --> 00:18:35,850
Now what.

305
00:18:36,570 --> 00:18:38,510
Well you've got 16 hosts here.

306
00:18:39,120 --> 00:18:39,540
OK.

307
00:18:39,540 --> 00:18:45,420
So our subnet is then going to fill in 2 5 5 2 5 5 2 5 5 x.

308
00:18:45,420 --> 00:18:45,690
Right.

309
00:18:45,690 --> 00:18:52,800
Because we're in this row slash 28 says it's gonna be a 240 when we drop down to the subnet mask.

310
00:18:53,180 --> 00:18:58,550
I'm going to make this a little bigger how many host sixteen minus two.

311
00:18:58,620 --> 00:19:00,190
We have 14 hosts.

312
00:19:00,450 --> 00:19:00,790
Okay.

313
00:19:00,810 --> 00:19:06,350
So the first non host would be a 1 9 2 1 6 8 1 0.

314
00:19:06,360 --> 00:19:10,020
Again still the same thing first first address.

315
00:19:10,020 --> 00:19:12,400
Last address is going to be what.

316
00:19:12,660 --> 00:19:16,260
1 2 1 6 8 1 15.

317
00:19:16,800 --> 00:19:22,040
So it makes sense zero to 15 is sixteen addresses usable space is 14.

318
00:19:22,050 --> 00:19:25,290
Because we take out the network and the broadcast.

319
00:19:25,290 --> 00:19:31,920
Now you could see something like this and then guess what you're segmented so because you're only using

320
00:19:31,920 --> 00:19:41,880
this little bit of space you can then in turn have something like this 1 9 2 1 6 8 1 16 slash 28 and

321
00:19:41,880 --> 00:19:47,730
then it starts the same way your subnet mask is actually the same because you're using a slash 28 you

322
00:19:47,730 --> 00:19:48,490
come through.

323
00:19:48,600 --> 00:19:49,880
You can just copy and paste that.

324
00:19:49,890 --> 00:19:51,810
The hosts are still the same.

325
00:19:51,810 --> 00:19:55,850
What changes here well your first address 1 2 1 6 8.

326
00:19:55,850 --> 00:19:56,720
Got one.

327
00:19:56,760 --> 00:20:02,660
16 and then your last address which is 1 9 2 1 6 8 1.

328
00:20:02,670 --> 00:20:04,650
That thirty one.

329
00:20:05,150 --> 00:20:12,770
So because this is smaller on the slash 28 side we can actually have multiple networks within like say

330
00:20:12,770 --> 00:20:16,990
a dot 1 0 dot one dot sixteen dot one dot thirty two.

331
00:20:17,120 --> 00:20:22,490
You get a multiple little networks here with only a small amount of hosts so maybe you have just a few

332
00:20:22,490 --> 00:20:29,660
servers in this range and you have like servers a b and c they go in a slash 28 and then you have another

333
00:20:29,660 --> 00:20:37,210
one of servers DC in your DB D E and F however you want to say it and you have more in that range case

334
00:20:37,220 --> 00:20:42,530
you can subnet this out into different things and we see subnets we see all kinds of stuff we could

335
00:20:42,530 --> 00:20:49,280
see phone servers user computers wireless all different sort of thing some companies get really specific

336
00:20:49,280 --> 00:20:50,150
with their subnet.

337
00:20:50,360 --> 00:20:51,540
Now let's try one more.

338
00:20:51,540 --> 00:20:53,940
Let's say we have a slash twenty three.

339
00:20:54,050 --> 00:21:02,090
Now I want to put in 1 9 2 1 6 8 1 dot 0 slash twenty three but that would be wrong.

340
00:21:02,090 --> 00:21:03,670
Why would this be wrong.

341
00:21:03,680 --> 00:21:07,130
This is actually going to be a zero and I'll show you why in a second.

342
00:21:07,790 --> 00:21:12,100
So we're no longer locking in the this this number anymore right.

343
00:21:12,110 --> 00:21:19,160
When we get below the slash twenty for the two fifty five all the way across for three of them.

344
00:21:19,160 --> 00:21:24,700
Guess what we're now have the ability to change is no other than what's locked in.

345
00:21:24,770 --> 00:21:26,530
So let's do adopt zero.

346
00:21:26,540 --> 00:21:29,300
We'll talk about why it's hit enter here.

347
00:21:29,450 --> 00:21:30,680
So the subnet on a slash.

348
00:21:30,680 --> 00:21:31,450
Twenty three.

349
00:21:32,030 --> 00:21:36,440
Well we're gonna do a two fifty four which is going to be a place holder of the X here to come in and

350
00:21:36,440 --> 00:21:40,120
say 2 5 5 2 5 5 2 5 4 0.

351
00:21:40,790 --> 00:21:42,410
And now again we're not locked in.

352
00:21:42,410 --> 00:21:47,270
So remember this two fifty five would lock in this dot one that doesn't happen anymore.

353
00:21:47,360 --> 00:21:51,100
So we've got two fifty five to fifty five 254 dot zero.

354
00:21:51,140 --> 00:21:55,580
We're actually going to start at zero here and we're gonna say the number of hosts that are possible

355
00:21:56,280 --> 00:22:06,320
it's five 10 five twelve minus two will say our network idea is 1 9 2 1 6 8 0 0 and our broadcast would

356
00:22:06,320 --> 00:22:12,790
then be 1 9 2 1 6 8 got 1 2 fifty five why.

357
00:22:12,820 --> 00:22:19,610
OK so we have the possibility now that we're spanning two ranges we've got five hundred and ten hosts

358
00:22:19,700 --> 00:22:20,950
in this network.

359
00:22:21,310 --> 00:22:27,800
And we have the ability to go between zero and one we've got two options now zero and one.

360
00:22:27,920 --> 00:22:34,700
So if we were to say another network if we wanted to get to like two we'd actually have to say 1 9 2

361
00:22:34,700 --> 00:22:43,160
1 6 8 2 2 0 slash twenty three it would be the same subnet mask same number of hosts but then this would

362
00:22:43,160 --> 00:22:51,340
be 1 9 2 1 6 8 8 2 0 1 9 2 1 6 8 3 2 fifty five.

363
00:22:51,470 --> 00:22:56,290
Again there's five hundred five hundred ten possible hosts in between this.

364
00:22:56,300 --> 00:22:56,860
Right.

365
00:22:56,930 --> 00:23:04,640
Because you've got to think dot 0 dot 1 0 9 2 0 3 all the way through 254 and again one dot one one

366
00:23:04,640 --> 00:23:06,990
dot two all the way through 254.

367
00:23:07,160 --> 00:23:09,800
So that equals five hundred and ten.

368
00:23:09,800 --> 00:23:14,200
Once you've hit that maximum that one dot 255 five then guess what.

369
00:23:14,210 --> 00:23:15,290
You start to.

370
00:23:15,350 --> 00:23:19,820
You have a whole new network here just like these smaller segments you get whole new networks on the

371
00:23:19,820 --> 00:23:21,380
bigger side as well.

372
00:23:21,410 --> 00:23:28,880
So what you need to know is that when I if I would put something like a 1 9 2 1 6 8 dot 1.0 slash twenty

373
00:23:28,880 --> 00:23:35,120
three that would have fallen into line with the one in the zero in our actual network ideas still would

374
00:23:35,120 --> 00:23:42,280
have been 0 0 and a one dot 255 would have been the broadcast here and you can double check this anytime

375
00:23:42,290 --> 00:23:45,620
you're confused you can double check your site or notation.

376
00:23:45,770 --> 00:23:52,430
So I'm going to bring over a Web site that I will show you here and this is just an IP addressing guys

377
00:23:52,430 --> 00:23:54,780
called IP address guide dot com.

378
00:23:55,040 --> 00:24:01,850
You bring this over and you scroll down just a little bit and I just put in 1 9 2 1 6 8 1 0 slash twenty

379
00:24:01,850 --> 00:24:08,410
three and you can see that it actually corrects me and says the first bit is 1 9 2 1 6 8 0 0 0.

380
00:24:08,420 --> 00:24:17,960
The last ones 1 9 2 1 6 8 1 255 total hosts is 512 minus two shows you that again first ip last IP you

381
00:24:17,960 --> 00:24:19,100
got your net mask.

382
00:24:19,160 --> 00:24:24,950
Very easy to use a cyber calculator here or an IP range to convert decider as well.

383
00:24:25,010 --> 00:24:26,380
So very useful calculators.

384
00:24:26,390 --> 00:24:30,950
But if you're not allowed to use these for like an exam purpose or something along those lines then

385
00:24:30,950 --> 00:24:34,580
using the cheat sheet that I've shown you is super useful.

386
00:24:34,610 --> 00:24:39,870
Now what I want to do is I want to try for three more subnets.

387
00:24:39,910 --> 00:24:40,770
I'm going to write these out.

388
00:24:40,800 --> 00:24:55,910
I must say 1 9 2 1 6 8 0 0 slash 20 to 1 9 2 1 6 8 1 one zero slash twenty six and 1 9 2 1 6 a dot 1

389
00:24:56,080 --> 00:24:58,200
0 slash 27.

390
00:24:58,240 --> 00:24:59,560
I want you to solve these for me.

391
00:24:59,560 --> 00:25:06,040
Tell me the subnet mask the host network and broadcast it with that being said this again is a very

392
00:25:06,040 --> 00:25:07,500
complicated topic.

393
00:25:07,570 --> 00:25:10,510
I did not pick this up the first time or the second time that I got it.

394
00:25:10,510 --> 00:25:16,420
If you're running confused right now perfectly normal you can go back and watch this video again try

395
00:25:16,420 --> 00:25:21,760
to pick up more topics try to understand it maybe I'm not the right instructor for this either I do

396
00:25:21,760 --> 00:25:27,520
recommend looking at other resources to completely fill in your knowledge gap if there is one that exists.

397
00:25:27,520 --> 00:25:32,920
Another resource that I'll link down is what is called Seven second subheading it is very useful a lot

398
00:25:32,920 --> 00:25:34,560
of students have recommended it to me.

399
00:25:34,660 --> 00:25:36,670
I'm going to push it forward as well.

400
00:25:36,670 --> 00:25:38,880
So go ahead and try to solve this.

401
00:25:38,920 --> 00:25:43,510
Understand that what you're after here is just understanding what a subnet is.

402
00:25:43,510 --> 00:25:43,800
OK.

403
00:25:43,810 --> 00:25:49,750
When you see something like this if a client sends you 1 9 2 1 6 8 1 0 slash 24 you're going to say

404
00:25:49,810 --> 00:25:55,330
hey OK I know that there's probably 250 for hosting that network and I know what I'm working with.

405
00:25:55,480 --> 00:26:01,900
If you see this 2 5 5 2 5 5 about 2 5 5 0 again you know that you're working with a slash 24 network

406
00:26:02,260 --> 00:26:03,330
very standard stuff.

407
00:26:03,340 --> 00:26:04,620
That's what we're after.

408
00:26:04,660 --> 00:26:06,630
I don't expect you to ever memorize this.

409
00:26:06,640 --> 00:26:12,820
I don't have this memorized like I don't come in here and say you know a slash 18 is a 2 5 5 2 5 5 1

410
00:26:12,820 --> 00:26:17,820
9 2 0 network and it's got sixteen thousand three hundred eighty four hosts I don't do that.

411
00:26:18,280 --> 00:26:18,610
OK.

412
00:26:18,630 --> 00:26:23,920
I have a cheat sheet I'll use a Web site if I need to for the most part what you need to understand

413
00:26:23,920 --> 00:26:29,870
is to 250 for hosts for a slash twenty four if that number has gone up to like a slash twenty eight

414
00:26:29,890 --> 00:26:34,690
you know you're dealing with less if that number is lower like a slash sixteen you know you're doing

415
00:26:34,690 --> 00:26:39,850
with a bigger network that's really what it comes down to unless you are working in networking and then

416
00:26:39,910 --> 00:26:44,290
these become more important but as a pen tester understanding how to read this understanding what the

417
00:26:44,290 --> 00:26:51,430
subnet is and just identifying it with very basic measures this is extremely useful so I'll get you

418
00:26:51,430 --> 00:26:56,800
over in the next video when we talk about solving these challenges and hopefully we got them all right

419
00:26:56,890 --> 00:26:58,240
so I'll see you over there in the next one.