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  1. Member
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    #1

    Default Subnetting for Dummies

    Hey Guys,

    I can't believe this but I'm having the hardest time grasping subnetting, and I know once I get this down everything will come naturally.

    Whats the foundation on learning how to subnet, especially doing it in your head, I'm great math, any ideas would be greatly appreciated!!!!
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  3. Skilled Hamburglar Monkerz's Avatar
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    #2
    What are you having troubles with? Seeing a netmask and trying to figure out how many hosts and subnets you get? Having a CIDR and trying to figure out hosts and subnets?
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  4. Senior Member
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    #3
    Quote Originally Posted by Meast View Post
    Hey Guys,

    I can't believe this but I'm having the hardest time grasping subnetting, and I know once I get this down everything will come naturally.

    Whats the foundation on learning how to subnet, especially doing it in your head, I'm great math, any ideas would be greatly appreciated!!!!
    Remember the commond numbers:
    Ie:
    /24 is a cblock 256 ips and the subnet mask is 255.255.255.0
    /25 is half of a /24 or 128 ips so the subnet is 255.255.255.128
    /26 is half of a /25 or 64 so the subnet is 255.255.255.192 (128+64=192)

    So if you have a /26 and it says something like is this a valid host address:
    192.168.1.64
    no, thats a network address

    192.168.1.127
    no thats a broadcast address

    192.168.1.193
    yes, valid hosts for that subnet are 192.168.1.193-254 (62 ips)

    /23 is 2 /24's or 512 and the subnet mask is 255.255.254.0
    /22 is 4 /24's or 2 /23's or 1024 ips and hte subnet mask is 255.255.252.0

    Also like for a /22 to find the 3rd octet its 4 cblocks - 256 = 252

    /32 is 1 ip
    /31 is 2 ips
    /30 is 4 ips
    etc.

    Before the test you probably want to right down /16 - /32, what the subnet mask is for those, and how many ips there.

    HTH
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  5. Senior Member miller811's Avatar
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    #4
    Quote Originally Posted by Meast View Post
    Hey Guys,

    I can't believe this but I'm having the hardest time grasping subnetting, and I know once I get this down everything will come naturally.

    Whats the foundation on learning how to subnet, especially doing it in your head, I'm great math, any ideas would be greatly appreciated!!!!
    here is a great place to start

    Subnetting Made Easy
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  6. Left for Android! =)
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    #5
    Quote Originally Posted by miller811 View Post
    here is a great place to start

    Subnetting Made Easy
    +1

    Made subnetting click in my head!
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