Subnetting Question Walk Through - Cisco CCENT

hey guys welcome to this extremely a great video this is a great subnetting video so if you guys are interested in learning subnetting i'm going to go through the steps i'm not going to get into it like fully fully but i'll cover all the steps needed to answer these questions here so what I have here on the right is my Cisco exam CD it's just like a practice exam it's just for the CCENT as you can see I got 139 questions and I've been going through them question by question so I believe this is like video 3 but this is going to be a great video it's going to be pretty long so bear with me but we're going to go step by step on how to answer these questions so what the diagram is implementing here is that obviously everything's set up all the routers are set up with rip version 2 and they have the no IP subnet 0 command as you can see right up here ok and what that command issues is when you're looking at the network and you know like if your network goes up by let's say 30 - you got your 0 Network then your 30 to network your 64 Network you just can't use any hosts in that 0 network so you can have like 1 92168 0.1 as an address you have to start at 192 168 3 2.1 for instance that's what the no IP subnet 0 means and what they want to implement is just routing between all the networks so these are all lands here as you can see this is a land right here there's a land there there's a land there there's a land there and these are even considered lands ok so in this diagram we have 1 2 3 4 5 6 7 lens so just to show you what a land is annoys and they just have a series of questions so out of these questions what what ones are true so for question a new PCs that are added to the land off router three can use any IP address between 192.168 201 to nine and one 92168 200 dot 190 so router 3 is this router here so this is the network so you want to identify the subnet mask here so it gives us a twenty eight so their network is 192.168.20.10 uh ting and you figure out what network they're in the address has to be within that network and that's what you would configure PC three with okay or any PC that connects to this router so what we're going to do is I'm going to show you guys my little cheat sheet that I have and this really helped me with subnetting I'm only going to show you the Class C version of it because we're going to be dealing with Class C networks here as you can see at all the subnet masks so what I do is I always start off with yes I'm using Microsoft Paint but who cares I always start off with my bit values so if you have any idea of what subnetting is you've got you know your 192.168.1.0 okay and you'll have a subnet mask of 255.255.255.0 okay so what that means is like when I say your bit value I mean any one of like these here opt X I can never pronounce that goddamn word but anyways within each of these dots here you got an 8 8 bits and each of those 8 bits has a value okay so you'll have 8 bits here okay so for instance two five five would be ones four five six seven eight dot one two three four five six seven eight one two three four five six seven eight and then zero means there's no value so zero zero zero zero zero zero zero zero okay yeah so that kind of implements this here okay so when you're looking at the subnet mask of 28 that's telling you it's a 28th bit so you got 8 16 24 then 25 I'll show you here you got 25 26 27 28 so with 28 you can see that your network goes up by well 16 if you would if you're if you know what I'm about to tell you now so you list each one of these 8 bits has a value and that value is what I use to understand subnet mask so the first bit right here going from left to right right is 128 and then you got 64 then you got 32 then you got 16 then you got 8 4 2 and 1 okay so that is just like an indication here okay and it just continues on and on and on so when it says the 28th that means your network goes up by 16 because you are using this network here this is the last bit so as you can see here you put your little pipe right here okay so that's telling you your network goes up by 16 if it was let's say 27 so this would be your 27th bit here you'd put your pipe here and this would be your network but that's not the case in this video so it goes up by 16 so you can start listing your networks so you got one 92168 200 so you'd go and you go 192.168 200 0 through 2 dot and what is it 16 so it'd be 15 because your next address would be the next network ok so your networks are how your eye peas are like so the router know is like okay so network 16 has the host I need to get to address 16 dot 50 ok so it kind of IDs your area here so the next network would be 192.168 200 dot 16 through 31 because 32 is your next 192.168 232 would be next and then you have dot 48.62 4.80 and it would keep going on on and on until you got to get to 192 so yeah you're only really missing the one the 176 but anyways it's asking if any PC was to join router 3 can use any IP I just between 192 168 200 dot 129 and 1 so let's just look for 129 so 129 would be in this network here right because 128 goes to dot 143 but 143 is a broadcast domain so it's used to broadcast to all hosts in this network okay so that's fine and 190 is in a different network which would be in this network down here or actually sorry it would be in the one network that I left out dot one seven six and that would go up to 191 so right away that you don't even really have to go any further because you can't issue IP addresses and different networks this network is 141 so it's in this network right here so it doesn't matter about this network down here it can't it can't do it it can only be issued between 129 and 143 so answer a is incorrect so we can scratch that off the list so question B if PC two were assigned IP address the down here dot 129 PC 2 could be working if both PC 2 and router to use a subnet mask of 192 so the default gateway is in 202 so whichever we figure out the network ID of 192 it has to be within 2 0 2 has to be in that network range for PC 2 to be assigned a 129 Network so to figure out the 192 what you do is to figure out the the network list is you would add these numbers up so 128 plus 64 equals 192 so that is the magic number so this is our network range so our first address in this example 10 1 68.9 9.0 would be 10.16 8.9 9.0 and then dot 64 and then dot 128 there's not too many here so I'll list them all dot 192 and 256 okay and like the command up here says you can use a zero network so you couldn't use this one even though it goes to 63 so that's 63 host you lose right there by issuing that command and it wants to know if you can get 192 or 129 okay so 129 looking over here is that's what pc2 were assigned would be in this network right here right right there 129 that's the next neck that's the next ID so that's fine but if you look up here the router is in 202 so the router is in this network and what's the golden rule you can't have IP addresses within the same LAN and two different networks if the communication will be lost so B is also incorrect so you can't use B so let's remove this let's start with C know if PC 2 were assigned IP address . 1:29 so it's pretty much you want the same ip address as be but the subnet mask is different it's 128 so remember up here how we did the the adding so you don't add it's 128 plus 64 is 192 plus 32 is 2 24 plus 16 is 240 plus you know 8 is 248 and so on you just keep adding the values so 128 in itself is just 128 so your network goes up by 128 so you would be looking at what's their IP 10 10.16 8.9 9.0 and then this network would be 128 and then 128 plus 128 is 256 and you can't use this network which goes to 127 so it's 127 house you lose right from that command and it wants IP address 129 okay so that is telling you that 129 is in this network right 129 is after 128 and the router has a - OH - well 202 is in this network so yeah that's correct if PC 2 was assigned the address of 99.1 - 9 right here then it could work with router 2 so that's right okay so d if a new PC there are sorry new PCs that were added to the land off router one can use any IP address between 193 and 223 so again it's like same kind of question as a so you want to look at the subnet mask so D goes up by 32 so your address here would be because 27 the 27th bit so 25 let's change that 26 27 and the subnet mask is 27 so again goes up by 32 so your first network is 192.168.1.0 and it goes on to 32 64 you guys get the idea and it goes all the way down to dot 192 and then to 24 and then 256 sorry for the sloppy I'm using a mouse okay so you figured out the network setup for this land up here so in judging out the IP address 199 you know that there in this network right here right 192 or 199 comes after so that's right so wants to know if if pcs can connect to dot 193 to 223 okay yeah first glance that sounds right because 192 so 193 is smaller than R is bigger than 192 smaller than 220 for 223 is smaller than 224 but what's what's the last IP address in a and in a network it's the broadcast so you can't use it because that's used for broadcast exactly what it is like you can send messages to all hosts on the network so no you you cannot use this scheme right here if it was 222 then yeah sure you can use it so you get it really got a watch because they're they're pretty tricky like that and it'll catch you on questions like that and through the exam so just to keep your eye out for things like that okay so I guess we're going on to II now so pcs that are added to our one can use any IP address between 193 and well I should have just kept that should it just kept that Network I want to fake it err sweet okay so what we're going to do is I'm going to clean this up a little bit here okay it's all cleaned up now so we were on question e so the new PCs that are added to the land off outer router one can use any address between 193 and 222 except from 191 and 192 so that's pretty much the same question only confirming that it's 222 right because 193 ten is in this network and 222 is in this network also and it is usable they're just trying to throw you off will except with dot one nine nine and dot two zero one yeah okay they're they're in here somewhere but who cares so yeah you can that's that's valid so for question F let's walk through that right now and I hate Microsoft Paint it's not bad but ok so for F new PCs that are added to the land off router three can use any IP address between 129 and 158 sorry for the reference I'm just saying the last octet because they're all Class C networks Class C if it was lower than classy they would be this number would be smaller than 24 but they're all bigger than 24 so right away it's all Class C networks set up so whatever it wants to know if people can use 129 through to 158 and we got a - 28 subnet mask so 28 if you continue the count here's 25 26 27 28 which is 16 so this is our magic subnet now 16 - last question something to get sloppy so our network goes up by 16 so again we go 1 9 to 1 6 8 and they got 200 dot 0 and it goes you know 1632 all the way down to what do they want to use 193 - err sorry 128 Wow 129 to 256 so we could put Network 128 to 128 to 144 to 160 and we can stop now because you can already see that the two addresses are in two different networks so the 129 address would be in this network here and the 158 network would be in this network here and like said you can't use addresses to different networks on the same LAN so f is wrong you fail okay so now we can check to see if we've covered everything and to see if we're right we can just show the answer down here and you know your answer this question correctly but I'm kind of glad because it was a good question to go through really explain a lot about subnetting so what I meant earlier about this video being class C related up here it just meant like these bits here how they go let me just show you because this is how I learned subnetting I just memorized this I wrote out the first bit so I went one 128 64 32 sixteen eight four two one and I would issue the ID so 25 26 27 29 30 31 32 and then I would des write the values like I forget the actual term of them but when you add them up like sometimes when you see the subnet mask like like this here 128 and 192 when you see subnet masks like that so what that is is just adding these up so this one is 128 192 - 24 - 42 48 to 52 54 to 55 but that's for Class C so you'd have your dot here and if their IP address was you know let me just use an example 192.168.0.0 18 okay so what that 18 means so this is their subnet mask that's two five five two five five two five five right here so those are all ones you know the whole bunch of ones they'd be 24 ones here for sure and then 18 it would hit a zero for this so the first bit is not on because this doesn't it 128 is way too big 64 no 32 no 16 okay so there'd be a 1 there because 16 is smaller than 18 so you're trying to calculate you're trying to add these up to make this number so 16 plus 8 is too much 16 plus 4 still too much it's not 20 so 16 plus 2 well yeah that's 18 so that's what it would look like in binary that's what you call binary and that'd be a dot there but that's just for Class C networks this here it all stays the same like the bit values like the way the networks go up will always be by this value here 128 64 32 you know you're not going to get a network that goes up by ten thousand four hundred and fifty million like so it follows this pattern what will change will be your ID here so for B you got you know a Class B Network is 16 bits so your first 16 bits I'm not sure if I've didn't even count so let's just say that's 16 bits and the rest would be zeros until you reach 32 like you can only have 32 bits okay so if you were dealing with a Class B what would increase would be your your hosts so your network would stay the same and you know like what let's say for instance this network here you can have 128 hosts per network okay but so a Class B what would like these numbers here would keep adding up and doubling so Class B would start off with 256 and then it would go to 512 and then it would go to 1024 and it'll go to 2048 and it would just keep going and going and going until you reached all the way to the end okay so I know if I'm getting a little sloppy here I didn't really intend to get this far into it I just figured I'd keep going so if you pick it up you pick it up if not then whatever and your values would still be the same so this would still be the first bit this would still be the first bit this would be the second bit this would be the fourth and then 8 and then 16 and then that would keep going following this pattern here and so that would like initiate your your networks you know what I mean so like you would start off like C Class C starts here so 24 would be this guy starting here so this one would be 23 22 21 20 19 so then if you've seen like a sub like an IP address of 192.168.0.0 then you know it's this okay so it's 21 so your network goes up by four and you can have four hundred thousand and twenty four house per network minus two so 1022 and what that means is I keep this in mind I'm going to refresh this here and get rid of everything so if your network goes up by two R by four and you're dealing with a Class B networks I know this is a little confusing up first so you got 10.1.1.10 soar Class B Network so let's say you're in this network the one dot network going to be 10.10 dot zero and you can go one it says you got 10,000 you know hosts you can go up each of these off Tech's 255 so you're next you're next IP address be 10 1 0 1 and then 10 dot 1.0 dot 2 all the way up you know dot 3 4 all the way up to 255 and then you would start in this one so your next network would be 10.1.1.1 10 1.1.2 until this reached four and that would indicate your network going up by like four and that would be the next network 4.0 and then it would start all over again so it just means you have a lot more hosts that's that's all it really really means but you can still use the same setup you can always just come in start writing your your binaries so you got you know the first bit second third four fifth six seven eight nine you know ten you can keep going until you reach thirty-two you know then you can start labeling them out that's what I do that's what I'm going to do I'm going to write my exam actually this Saturday and when I walk into that room it's not cheating and I'm right now my little chart here so if I get a subnetting question you can take half the time out of it the hardest part is just multiplying the network so if it goes up by 16 to go 0 16 32 48 64 80 you know etc etc but anyways I'm out this I've really dragged on here at the end but hey if you picked it up if it helps I find that's the best way to sub that is just to memorize that little chart and like I said once you actually write that chart down and see the pattern you're gonna you're gonna thank me for this all right thanks guys

Channel: Paul St.Onge

Views: 17,010

Keywords: tech knowledge computers, tech knowledge comp, tech knowledge, windows 7, how to, paul st onge, paul, how to subnet, subnetting, easy, CCENT subnetting, how, to, solve, problem, CCENT, guide, concepts, walkthrough, Through, CCNA, study, Walk

Id: c2lC8tDaiRk

Length: 32min 38sec (1958 seconds)

Published: Sat Oct 13 2012