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    What does the slash (/) mean in IP address allocation?


    This is probably very much a newbie questions...

    When people have talked to me about IP address range allocation they have discussed IP's with the use of a slash on the end of them, eg:

    192.168.0.1/25 or 192.168.0.1/30

    What does this /25, /30 mean on the end of IP addresses?

    I am going to set-up a couple of servers soon, and the network admin mentioned what do I want as far as IP addresses go. They started talking about allocations that use this slash (/). Basically, I want 30 individual IP addresses that I can bind across 3 servers (10 per server). What should I be asking?

    Are there any basic networking tutorials online that can help me understand this type of 'network talk'?

    Thanks
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    The slash is how many subnet mask bits to use. since the use of classless routing you use slash instead of saying class A or B whatever. example..

    192.168.1.1/24 is 192.168.1.1 255.255.255.0

    255.255.255.0 is using 24 of the 32 bits to create the subnet.

    in binary it looks like this..
    11111111.11111111.11111111.00000000

    so a /30 would look like
    255.255.255.252 or in binary
    11111111.11111111.11111111.11111100

    the remaing 00 is for hosts the 1's are the network

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    • Sepodati agrees
    Last edited by juniperr; May 9th, 2005 at 07:54 AM.
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    Thanks juniperr
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    Juniper is correct. The term for this is CIDR.

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    • juniperr agrees : juniperr is correct LOL!

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