Calculating number of subnets question

Discussion in 'Network Routers' started by steve, Jul 29, 2010.

  1. steve

    steve Guest

    I get most of the subnetting things, I think.
    How to calculate how many subnets / hosts / Network ID / broadcast ...
    ACCEPT !

    I don't understand how to calculated subnets based on subnets like

    I'm NOT confused (I don't think) about class or unclassfull / cidr stuff.

    I'm just use to doing supernetting (I think its call) but confused when you
    have an IP that is a full Octet.

    for example
    Here is my math on the above address.
    0000001010.00000001.00000000.00000001 >IP
    1111111111.11111111.11111111.00000000 >Subnet Mask
    0000001010.00000001.00000000.00000000 Network IP using Anding.
    .11111111 I just add 1's to host bits to get broadcast

    I think that there are 8 subnet bits in the third octet and 8 host bits in
    the 4th octet, that should give me 256 subnets (minus 2) and 256 hosts
    (minus 2)

    HOWEVER when I look at an ip subnet calculator I see that there are 65536
    subnets available and 256 hosts. I'm confused where the 65536 subnets comes
    from (other than its 2^16=65536) Where did the 16 bits come from for the

    steve, Jul 29, 2010
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