How to Subnet – The Easy Way

How to Subnet - The Easy Way



hey guys it's George coming at you with another video and I hope this video finds you well I was in my networking class and right now I'm finishing up my bachelor's and I had some homework here and I've been doing the CCENT I passed that exam about a week ago and I feel pretty comfortable with subnets and I just kind of wanted to make it tutorial on how to do subnets the easy way it's really not difficult learning how to do subnets at all and I feel like we can go through it in a in a methodical manner and it's not something that you should be worried about if you're doing your CCNA or if you're taking some kind of networking exam or you just want to know about networking subnetting is not something that's unaccomplished ball it's very comfortable so let's go ahead and start with this example okay now I will say that this is somewhat of a complex example I will probably be rolling out some other questions that are less complicated than this but this is the one I have available for my homework and of course I'm posting it after the day I have to turn it in so okay so we have a computer whose IP address is one 98.1 three to 202 dot 255 now this here is actually a kind of a Mohan surely no that's actually a valid valid IP address it just kind of looks funny because 255 you normally don't see that okay and the subnet mask is 255.255.255.0 which of the following IP addresses are in the same subnet as this computer please show you how you get your solution and then you have these here so let's go ahead and work out how to do that but first I want to show you guys pretty much how binary works okay so we've all heard of bits and bytes or at least I hope and if not a bit is real all of that a bit is really is just a 1 or 0 that's all it is it's a yes or no and honor enough so that's that's it a byte the way I like to remember it is that when I say you can have a bit of my burger you're going to take a little bot a little bit just take a little bit of my burger and I say yeah you can have a bite bite it's bigger than a bit so a byte is eight bits an example of that would be about one one zero zero one one zero zero that is a sequence of eight bits one two three four five six seven eight as you can see there are eight bits here is one there's two three four five six seven eight there's eight bits all together here so that's it so far now what is a bit mean so pretty much the way you calculate what each bit stands for and what each byte equals to is by utilizing something called base two and all base two is it means that it's 2 to the power since I don't have the power I'm just going to use a carrot that 2 to the power of n which is any number so for example if I said for example that we had eight so which in this case is true because we have eight bits so if an example of that would be 2 to the 8th let's go ahead and do that on the calculator even though I know that that equals 256 off the top of my head but I'm just going to go and bring up a calculator just to prove that to you let's go ahead and do a scientific calculator and – let's do let's see now how do we do this – to the 8th – 56 okay so awesome – 56 however I would like to say that if you were to turn on every one of these bits so one two three four five six seven eight what is that equal to it actually doesn't equal to 56 it actually equals to 55 and the reason for that is because computers consider zero counts so zero is one other place so if you were to add that one place to 256 that would equal to fit out to 55 that would equal to 256 so the range from zero well the way I like to think of it is that the range from zero to 255 if you can choose 0 and 255 is 256 so that's the way I like to think of it all right so now that we got that out of the way now I just told you that eight bits together like this once is equal to 255 now why is that that's because each place here holds a different value if it's turned on so the order from left to right is like this 128 64 32 16 8 4 2 1 so you notice that there's 8 1 2 3 4 5 6 7 8 so for example let's say I were to turn on that bit alright let me just go ahead and do it down here so if I did a 1 here 0 here 0 here 0 0 and 0 to 0 what you do is you look at this then you say that's on so that means that this place up here is actually on so let me go and format this I'm going to format the font to bold let's make that 12 and I'll never mind that actually does everything that way let me undo let me do font and regular 11 okay so 1 0 0 0 0 1 0 1 0 so the way you calculate this is you know that 1 is on so that's 128 plus 0 okay so we know it's 0 is that means that the 64 place is off off off off off on so that means that we have to add this place value to okay and then it's off so this would actually equal 1 130 do you understand that so hopefully you you do understand it so let's say I have 0 0 all right you know what let's go ahead and just do a subnet at 0 0 at 1 1 0 0 0 0 0 0 so try to do this one by yourself really quick see if you understand the flow okay go ahead pause the video right now okay if you haven't pass the video that's fine because we'll go ahead and go through it again so this one's turned on so that's 128 Plus this one's turned on so that's 64 and the rest are 0 so that means that they're off so there's no more adding to be done and while 128 plus 64 is 192 so that's a pretty much a concept there so that's kind of the way well that is the way binary works all right so now what does that have to do with anything so we have our subnet mask I was actually going to show you something but I'm going to show you this instead we have our subnet mask here now typically on our computer so I'm going to go ahead and show you I changed my mind about showing you that now I am going to show you if you were to do an IP config on your computer your card typically has a subnet mask of 255.255.255.0 now what does that mean all that means is how many Network bits and how many host bits are in your network so for example go ahead and minimize that if we had 255 dot 255 255 0 remember what I told you up here that 255 means all of them are ones so what this means is that this is 1 2 3 4 5 6 7 8 . so that's this part here 1 2 3 4 5 6 7 8 . that's this part here in the last part of again again 1 2 3 4 5 6 7 8 . and that's this part and the last part is 0 but it's all 0 so it's 1 2 3 4 5 6 7 8 so there you go you have 4 segments here like that so that's 255.255.255.0 okay so that means that you have this many Network bits and we won't go into that right now and we have this many host bits so pretty much this means that you can support 255 total hosts well actually not really because it's really 256 minus 2 and we'll go into that in a little bit so let's go ahead and grab the subnet here that we had 2 5 2 so 2 5 2 is actually so let's go back here so it's 2 5 5 2 5 5 2 5 2 so it's 2 4 5 2 4 5 to 15 that this third octet each of these is considered an octet by the way because it has 8 bits this one's going to be 128 plus 64 plus 32 plus 16 plus 8 plus 4 then the 2 and the zeros are all turned off so if you were to add this that would equal to 252 ok so you can do that using these numbers up here I already have these memorized so no problem so 1 2 3 4 5 6 7 8 because that is still a 0 and you'll never see an instance in the subnet where you have a whole bunch of ones then a 0 0 then a 1 again then zeros it's always going to be all ones on one side and all zeros on the other side and ones go first the subnets and zeros go after that ok so that is our subnet so why did I go over all of this now here this is probably the most important bit of this entire subnet so we need to know what place this is in in reference to this octet here so we know that this one here is the one place this one is a 2 this one is the 1 1 2 then 4 so this is the fourth place so that means that it that calculates our increment what is it I put Inc that's 4 ok so now what does that mean well that means that each of our subnets are going to have an increment or each of our networks in our subnet are going to have an increment of 4 so the first network would be 0 the next one would be Network 4 then 8 then 16 so now what are the network IP addresses because the network have to have an IP address and so does the broadcast so we'll go over that right now so here are our networks here are networks okay so we go back to the problem it's one 98.1 3 2 dot lil Adela let me just go ahead and move that up that's not doing what I want to do let me go ahead and make that smaller let's go ahead and do that okay all right so this here is the subnet so it's a Class C subnet so that means that it's typically on a 255 255 dot 255 dot 0 and then we haven't gone over that so don't worry about it but here we have a big clue on where we're going to start with our network so right here all the ones means that we're going to keep these first two octets the same so 1 98.1 3 2 dot and then here we're going to start at 0 0 dot 0 so because the here's where the octet where we figured out our increment so we start at 0 and do that at 0 as well and that's going to go to 1 well let's start off with the starting points so 0 dot 0 so if we go for in the increment we're going to add 4 to this right here to this this octet so this is where that the increment was found so that would be 1 on a 22 dot 4 dot 0 ok so now this is through 1 98.1 32.3 dot 255 3 dot ok so 1 98.1 32.4 dot 0 the number right before this number is 3 dot 255 that's because 255 is the highest number we can take like I mentioned before if I were to just go up one more that would be 4.0 so that's why I like doing this side first to determine the network addresses and the broadcast I have addresses are these on this side so we're going to go down that way so one I need that one 32.8 dot zero and we keep on going 198.50 m so on and so forth and we we continue that we continue doing that I'll go ahead to another end so what's right before 7.0 it's 18.1 32.7 dot 255 so and so on and so forth so now here we can go on forever however the IP address that we're trying to reach is 1 98.1 3 2 – OH – so we're going to go ahead and skip all the way to 1 and 8.1 3 2 dot 200 now why 200 I know 200 is going to be a network because it's actually dividable by 4 so if I were to do 200 divided by 4 it would be an even number so that means that that is a a good IP address a good network address so again I'm going to go ahead and do the nice one 100.1 32.2 Oh what 204 that's right because you add 4 to this number dot 0 and that's going to be 2 1 98.1 3 2.2 o3 because this is the last one now what 255 correct so this here is a range where is the network that this IP address is in so notice that 202 255 is right in between here so that means that when the questions asking us which of the IP addresses in the same subnet we need an IP address that is also within this range and the only one would be this one here 198 lambda so skip this 201 dot 205 so 201 205 you would agree is between here so that would be the answer answer see all of the other ones are for example this one here would not be in the same IP address because it's both in the same network because it's before this 200 204 is after 203 255 206 is way after so that's how you determine that so hopefully this has given you somewhat of an idea of how you can answer these type of questions if you guys have any questions I know this was very quick but I thought that maybe this will help out some people and if it did be sure to leave a like down there and if you have any questions or any concerns or comments be sure to leave them down there and hopefully this was helpful to you all and I'll see you guys next time bye bye

47 Comments

  • This was a big help both with subnetting, and understanding binary. Thank man!

  • CykaNugget says:

    One of the best part about this video is the satisfying sound of the keyboard XD

  • Leo Garza says:

    Haha no way Jorge! I didn't know you had a channel. Lol I am also studying computer information system! Nice channel! This has really helped me understand Sub netting more ! Sweeet

  • Chris Ford says:

    You earning a BA and have already passed the CCENT, Awesome! Now for the ICND2. For people out there, you can either take the 1-Test=CCNA (not recommended) or you can take Test-1=ICND1=CCENT + pass Test 2=ICND2 = Becomming a CCNA. Why go this route? Answer: People get lazy, too much info to process and people do not speak binary. Of course there are other reasons also. IMPORTANT: No school (university or College) encourages or Demands Tech Students to attemp to take these test. I can not stress how important passing both tests are. I got a job because I failed the CCENT by a few points. And At a BANK!!!! Why? No other candidates attempted to test. Plus, I earned both CCENT+ICND2 in 90 days!!!! The bank paid for the tests! If you pass, THEY PAY! Hard as it was, I finally did it! Please take these words of advice. Skip all MS and NET+ however Security+ is a must! I promise you- if you learn, pass YOU WILL NEVER BE OUT OF A JOB! Trouble is YOU MUST PASS and MAINTAIN your credentials. Buy your books on Amazon!!!!! Congratulations Dude! Caution: Once the bug bites you, testing can become addictive! These test are very hard, expensive, challenging, demanding and impossible to know everything, but is worth learning "what" computer already do everyday= and that is Binary communications. Congrats again!

  • Fabio says:

    This taught me that when in doubt go with C

  • Icanthelplt says:

    This was an awesome video man. Thanks!

  • Capten says:

    :: batch script that converts a decimal number (up to 255) to binary

    @echo off
    cls
    color 0a
    mode con: cols=64 lines=30

    goto :Main

    :Main
    cls
    echo.

    set bit1=NULL
    set bit2=NULL
    set bit4=NULL
    set bit8=NULL
    set bit16=NULL
    set bit32=NULL
    set bit64=NULL
    set bit128=NULL

    echo Enter decimal number to be converted:
    echo.

    set /p dec=
    echo.

    goto :8bit

    :8bit

    if /i %dec% lss 128 (
    set bit128=0
    )
    if /i %dec% lss 128 (
    goto :7bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 128 (
    set bit128=1
    )
    if /i %dec% geq 128 (
    set /a dec=dec-128
    )

    goto :7bit

    :7bit

    if /i %dec% lss 64 (
    set bit64=0
    )
    if /i %dec% lss 64 (
    goto :6bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 64 (
    set bit64=1
    )
    if /i %dec% geq 64 (
    set /a dec=dec-64
    )

    goto :6bit

    :6bit

    if /i %dec% lss 32 (
    set bit32=0
    )
    if /i %dec% lss 32 (
    goto :5bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 32 (
    set bit32=1
    )
    if /i %dec% geq 32 (
    set /a dec=dec-32
    )

    goto :5bit

    :5bit

    if /i %dec% lss 16 (
    set bit16=0
    )
    if /i %dec% lss 16 (
    goto :4bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 16 (
    set bit16=1
    )
    if /i %dec% geq 16 (
    set /a dec=dec-16
    )

    goto :4bit

    :4bit

    if /i %dec% lss 8 (
    set bit8=0
    )
    if /i %dec% lss 8 (
    goto :3bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 8 (
    set bit8=1
    )
    if /i %dec% geq 8 (
    set /a dec=dec-8
    )

    goto :3bit

    :3bit

    if /i %dec% lss 4 (
    set bit4=0
    )
    if /i %dec% lss 4 (
    goto :2bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 4 (
    set bit4=1
    )
    if /i %dec% geq 4 (
    set /a dec=dec-4
    )

    goto :2bit

    :2bit

    if /i %dec% lss 2 (
    set bit2=0
    )
    if /i %dec% lss 2 (
    goto :1bit
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 2 (
    set bit2=1
    )
    if /i %dec% geq 2 (
    set /a dec=dec-2
    )

    goto :1bit

    :1bit

    if /i %dec% lss 1 (
    set bit1=0
    )
    if /i %dec% equ 0 (
    goto :ErrorCheck
    )
    if /i %dec% geq 1 (
    set bit1=1
    )
    if /i %dec% geq 1 (
    set /a dec=dec-1
    )

    goto :ErrorCheck

    :ErrorCheck

    if /i %dec% equ 0 (
    echo Conversion success! & goto :conversion
    )
    if /i %dec% neq 0 (
    echo Conversion failed!
    )
    echo.
    pause

    goto :Main

    :conversion
    echo.
    echo %bit128%%bit64%%bit32%%bit16% %bit8%%bit4%%bit2%%bit1%
    echo.

    pause

    goto :Main

  • Very useful and clear aswel!. Thank you very much!

  • That is possibly one of the best explanations I have seen in years.
    Thank you!

  • BARRIGHINI says:

    wow you did a great job explaining this you just earned yourself a new subscriber.

  • This was very helpful. It did not make much sense when my instructor explained it but this made it easy to understand. Thank you!!

  • Trung Phung says:

    here, take the like sir. my lecturer tried to explain your same method and made everything even more confusing

  • Very good video, this cleared things up for me, haven't been to school in a long time and you helped me understand subnetting in a simple way. Should help me out with my job, thanks!

  • cbdcdd says:

    Brilliant! Thank you so much for this. You are a GREAT teacher.

  • Jon Joseph says:

    Helps a lot as i have a lab that makes us split up networks and defining their subnets and net ids

  • Mark Spott says:

    Hi, Thanks for the great presentation! Would like to see a lot more examples of verifying and identifying "which network" belongs to which "network-range". These are the most prevalent questions and task that instructors and exams challenge students with. Also write down the FINAL block RANGE…again just for verification that we know the end block. 2 to the ninth should be it…but seeing someone else confirm the Final Block and The Final Host Range is a great comfort that we have and are interpreting the full allocations of network blocks and host ranges properly. Great concise job!!! Extremely Helpful!!!

  • luv1138 says:

    Thanks for sharing. I am preparing myself, because Im taking N+ test at the end of the month 🙂

  • Abby Travis says:

    Thank you! My professor taught me a much more confusing way!

  • Vince B says:

    It was very quick, but very clear at the same time. It was extremely helpful!

  • Thank you sir!, That helped a lot <3

  • ************************************************
    *********LINK TO .TXT FILE********************
    ************************************************

    (zippyshare)
    http://www6.zippyshare.com/v/E4wPFp5e/file.html

    or

    (Instant download)
    http://www6.zippyshare.com/d/E4wPFp5e/311374/Subnetting.txt

  • MrSlm1982 says:

    Thanks for the course, this was actually the easiest way for me to understand it.

  • dj3ss3nc3 says:

    awesome quck little guide, thank you  for this!

  • God Bless You Brother…. You just saved my life man!!!! Much Thanks!

  • A million thanks to you dude. I couldn't understand this even after taught repeatedly at the university(poor education system, I guess), but anyway thanks a lot.

  • I really appreciate this video,i just start CCNA today and i could not understand what the teacher is talking about,because for her its easy due she knows but what about the people who don't know,well i try to understand and follow the class and i got it complicated,when i watch this video i understand exactly what she was talking about,thanks for the video man its really help a lots,keep it up.

  • great vid buddy.. good explanation.. keep it up…

  • great video .. perfectly explained .. subnetting deff made easy now thanks to ur tutorial

  • a little confusing at first but very simple once you get it

  • mo da says:

    very helpful example… thank you very much…

  • Amanda W says:

    Subnetting is the next chapter in my Server Basics class, and this is really helpful! Thanks for helping me be a step ahead 🙂

  • thanks a bunch guy. i'm a bit stuck but not with how you explained it. i think i'm just trying to get a bit deeper into subnetting. but this is hugely helpful.

  • Eyon says:

    I love you, thank you for making a simple video that goes over everything. I understand it all now!

  • W Vitols says:

    Hello Jorge 
    Good Video
    Iv'e got a netgear WNDR3700 router in a home network.
    My IP address is 192.168.1.0 with  255.255.255.0  as subnet mask.
    If I can change my subnet mask to 255.255.0.0 will
    1.  the address 192.168.34.68 THEN be able to send me packages
    2. will I THEN be able to send packages to 192.168.34.68

    Thanks in advance Walter

  • Thanks for the Video Studying for my Exam Tonight and it's Making sense

  • I'm also working on my degree and you've explained it in a way that my profs couldn't.  Thanks!

  • WeGotBellys says:

    Thank you so much, i watched many videos and none of them told me about the increment. Now that i know this subneting has become so easy.

    Cheers

  • Andre Silva says:

    Subnetting is something really scare to me.
    How would I subnet a network for 80, 40 20 hosts using the class C?
    Thanks for your helping. 

  • sevenauz says:

    hmmmm.. If it's a Class C network which it is, then the three octets should be the network i.e 255.255.255.0 and you will be borrowing bits from the four octet …my questions is .. how many host IPs you will be having by having a subnet mask of 255.255.252.0 ?..just got confused !!!..need to refresh my subnetting again 😀

  • Thanks for the comment. I made another video that's simpler than this one.

  • Ruben Carpio says:

    hi.. i think you need to touch a little more on why you picked 200 (divisible by four). When presented with another IP that doesn't 204… what number would that person pick next??

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