Question Regarding Subnetting

Discussion in 'Networking & Security' started by Sayth, Jun 19, 2008.

  1. Sayth

    Sayth Gawd

    Messages:
    618
    Joined:
    Oct 7, 2001
    If I'm using subnet mask of 255.255.192.0
    How do I find the dividing line between subnet 1, 2, 3 and 4?
    I'm studying for the Network+ exam and was looking for a trick of the trade... Math algorithm or something ya know? :p

    thanks
     
  2. atomiser

    atomiser Gawd

    Messages:
    619
    Joined:
    Jun 12, 2004
    255.255.192.0 denotes that your networks will go up in 64's on the third octet... does that make sense, or do you require further explanation? i can break it down if required...
     
  3. Sayth

    Sayth Gawd

    Messages:
    618
    Joined:
    Oct 7, 2001
    Okay so the subnets for 172.16.0.0 would be

    172.16.0.1 to 172.16.63.254 --- Invalid
    172.16.64.1 to 172.16.126.254
    172.16.127.1 to 172.16.191.254
    172.16.192.1 to 172.16.254.254 --- Invalid (or 172.16.255.255 ?)

    ?

    I think I understand what you're saying...
    64 because 255-192=63 ?
     
  4. Rabidfox

    Rabidfox Limp Gawd

    Messages:
    282
    Joined:
    Oct 6, 2005
  5. Sayth

    Sayth Gawd

    Messages:
    618
    Joined:
    Oct 7, 2001
    That is awesome!

    yeah 256-192=64
    I figured that but when you count 0 then 0-63 = 64 numbers.
    So that's great guys thank you!
    I hope someone else benefits from this post.
     
  6. Mabrito

    Mabrito [H]ardness Supreme

    Messages:
    7,004
    Joined:
    Dec 24, 2004
    When I took Network+, there was nothing on subnetting. I wouldnt worry about it too hard about it for the exam. If there is even a question it just be on what is the purpose of subnetting. No math. It is good to know and if you are going into networking, its a must, but as for Network+ it isnt a must.
     
  7. Rabidfox

    Rabidfox Limp Gawd

    Messages:
    282
    Joined:
    Oct 6, 2005
    to go anywhere, anywhere at all, in the networking world requires you to subnet in your head on the fly. Don't do boolean algebra with bits, just use the magic number and you'll figure it all out. If you don't understand subnetting, you won't get far at all.
     
  8. Sayth

    Sayth Gawd

    Messages:
    618
    Joined:
    Oct 7, 2001
    Okay yeah I wasn't sure if it was on the exam or not, but I wanted to make sure to understand it as I am hoping I can go for my CCNA next month....
    I took CCNA1-4 in college a year ago and didn't do the exam... now I'm kicking myself, but I didn't grasp the subnetting concept then anyway.
    After the Network+ course I completely understand it. I think it's teacher quality you know.

    But thanks again!
     
  9. violinist

    violinist n00b

    Messages:
    5
    Joined:
    Jun 19, 2008
    if you go for the icnd1 and 2 , which is ccna divided up into two tests, believe me, you have to know how to subnet. Both simulations on the icnd1 had subnetting. Troubleshooting requires it, setting up a network needs it,you just can't know networking without it. One particular website has a test specifically for ip addresssing. And Nat requires subnetting. I,m sure you get the picture.
     
  10. violinist

    violinist n00b

    Messages:
    5
    Joined:
    Jun 19, 2008
    http://johnsontraining.com/Extras/Subnetting_Basics.ppt


    I think this website is pretty good, as it breaks down subnetting into its crucial parts that enable you to quickly figure out subnets and ranges very quickly. The icnd1 and 2 are timed tests . You have to know the answer or figure them out very quickly.
     
  11. berky

    berky 2[H]4U

    Messages:
    2,233
    Joined:
    Aug 28, 2001
    i thought i heard somewhere that tests like this and the ccna are doing away with questions on the old way of subnetting? (ie. losing the first and last subnets). anyone know if this is true? i could go on my rant again about doing subnetting like this, but i'll refrain :)