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    SubNet MASK (URGENT)

    Some please i want to know in detail about the SubNet Mask... like in C Class IP's subnet is is ther any other way i can change the subnets according to my requirements and what is the real reason for using subnets....

    A mask used to determine what subnet an IP address belongs to. An IP address has two components, the network address and the host address. For example, consider the IP address Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network.

    Subnetting enables the network administrator to further divide the host part of the address into two or more subnets. In this case, a part of the host address is reserved to identify the particular subnet. This is easier to see if we show the IP address in binary format. The full address is:


    The Class B network part is:


    and the host address is


    If this network is divided into 14 subnets, however, then the first 4 bits of the host address (0001) are reserved for identifying the subnet.

    The subnet mask is the network address plus the bits reserved for identifying the subnetwork. (By convention, the bits for the network address are all set to 1, though it would also work if the bits were set exactly as in the network address.) In this case, therefore, the subnet mask would be 11111111.11111111.11110000.00000000. It's called a mask because it can be used to identify the subnet to which an IP address belongs by performing a bitwise AND operation on the mask and the IP address. The result is the subnetwork address:
    Subnet Mask 11111111.11111111.11110000.00000000
    IP Address 10010110.11010111.00010001.00001001
    Subnet Address 10010110.11010111.00010000.00000000

    The subnet address, therefore, is

    hope this helps
    mujh sey khushiaan ley gaya aur degya kagaz kay phoool
    abb meray ghar mein paray hain jabaja kagaz kay phoool


      Meray Roz O Shab k Nisaab Main Meray Paas Apna To Kuch Nahi


        This is help u to manage ur subnets.

        Good luck.


          This one is better one, just recommended by our Network team .. they use this one.


            Originally posted by Najim:
            This one is better one, just recommended by our Network team .. they use this one.

            Here is another one

            This one by solarwinds is excellent and you won't need any more subnet calculators any more. Also they have a free tftp server which is the best one I've ever used (Much better than Cisco tftp server).