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VLSM frustration!

Discussion in 'Routing & Switching' started by Greens85, Nov 20, 2014.

  1. Greens85

    Greens85 Bit Poster

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    Hi All,

    I am part way through studying for the CCENT and I've spent a fair amount of time on subnetting (as I presume many do). I can now get the net ID, broadcast and usable hosts right 99.9% of the time (maybe not as fast as I need to, but the answers I get are correct. That said, I just can't get my head around VLSM. In particular, answering questions like this;

    https://learningnetwork.cisco.com/thread/68064

    Obviously, like most things there are tonne of resources on the internet for learning this. However, nothing I've tried seems to click. I thought I was getting somewhere using this method;

    2-4 Variable Length Subnet Masks (VLSM) - Free CCNA Study Guide Free CCNA Study Guide

    However, I am still getting the wrong answers.

    Can anyone offer any resources they have used that worked for them or even any general advice? I'm sure it's one of those things that will click eventually but I'm feeling frustrated with this at the moment.

    Thanks in advance.
     
    Certifications: BSc (hons), MCP, MCTS
    WIP: CCNA
  2. ITpack tsam

    ITpack tsam New Member

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    Hi Greens85,

    It is all about subnetting a subnet. Using FLSM we can subnet only equally. But using VLSM, we can sebnet according to our actual IP address requirement. Refer following links for more clear explanation.

    Regards, tsam.
     
  3. Coupe2T

    Coupe2T Megabyte Poster

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    It does take some time, but it's just subnetting the subnet. It's the same thing you are doing with subnetting, just that you are generally starting with a smaller pool.

    Kinda hard to explain, but been many a post on here, people the exact same problem but keep attacking the problems and it will come.

    Just think of it like pie charting, you are splitting the pie (Example a /24 subnet) into smaller chunks. So if you took one extra bit for network, and went /25 then you would have 2 parts to that pie.

    10.0.0.0/24
    cut in half to 10.0.0.0/25 and then 10.0.0.128/25 (first extra bit of an octet is equal to 128, so you have .0 to .127 and then .128 to .255, although usual rules apply for broadcast and so forth).

    Feel free to message directly if you need help and I will try to explain a bit further, this is a very quick vague example so might not capture all of the details that you need.
     
    Certifications: ECDL, Does that Count!?!
  4. Zunar-J-5/9

    Zunar-J-5/9 New Member

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    I feel your pain. I'm going through the same thing myself. Just keep at it. I thought I'd never break through the wall but now I think I have. you just have to practice practice practice until it comes out your ears eyes and nose. :) just kidding.... sort of :)
    I just finished the practice exam study session for part 5. and have finally, after many passes, gotten them all right, and
    even better am understanding the process.
    cheers....
     
  5. kenneth

    kenneth New Member

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    i have a better suggestion. have you visited the Cisco Game about Subnetting?if not go ahead and try it.
    then try to read the book of Todd Lamle. Good luck to you!!!!
     
  6. Zunar-J-5/9

    Zunar-J-5/9 New Member

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    Kenneth,
    great tip.
    here's a link to several other games people may enjoy, including the one you mention
    learningnetwork.cisco.com/community/learning_center/games

    can't put the http in front ; <5 posts
    most browser should handle it ok anyway, just can't click have to cut/paste
     
    AGlenday likes this.
  7. kenneth

    kenneth New Member

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    actually i enjoy that game and help me to pass the my CCNA exam. even though at first i really don't get how they compute that. But what is the most important with that game is the time pressure :).
     
  8. SimonD

    SimonD Terabyte Poster Moderator

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    There was also a great Cisco game for subnetting as well, I used to play it on my iphone all the time (subnetting, I used to hate it).
     
    Certifications: CNA | CNE | CCNA | MCP | MCP+I | MCSE NT4 | MCSA 2003 | Security+ | MCSA:S 2003 | MCSE:S 2003 | MCTS:SCCM 2007 | MCTS:Win 7 | MCITP:EDA7 | MCITP:SA | MCITP:EA | MCTS:Hyper-V | VCP 4 | ITIL v3 Foundation | VCP 5 DCV | VCP 5 Cloud | VCP6 NV | VCP6 DCV | VCAP 5.5 DCA
    WIP: VCP6-CMA, VCAP-DCD and Linux + (and possibly VCIX-NV).
  9. kenneth

    kenneth New Member

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    if only i could upload the exe file i downloaded in net to help you guys. just keep in mind that once you master the subnetting VLSM is easy.:D
     
  10. SimonV

    SimonV Petabyte Poster Administrator

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    Zip it and upload it.
     
    Certifications: MOS Master 2003, CompTIA A+, MCSA:M, MCSE
    WIP: Keeping CF Alive...
  11. kenneth

    kenneth New Member

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    i don't have any backup in my usb drive and my desktop is currently down. i'm still fixing it. anyway once i finish to repair it then i will upload it.
     
    SimonV likes this.
  12. kenneth

    kenneth New Member

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    hi sorry if it took too long to visit this thread again. by the way this is the application i use in subnetting
     

    Attached Files:

    AGlenday likes this.

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