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How does Subnetting Work?


I am not really sure how did this figure example get the broadcast address and the usable host addresses.

marked as duplicate by mailq, Iain, Shane Madden, Sven, Massimo Nov 6 '11 at 22:01

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  • 3
    Since they speak about a Class C network, you better drop this resource altogether. CIDR has replaced subnet classes years ago. – Sven Nov 6 '11 at 21:44

first of all im no network expert so correct me if im wrong, i will explain in the way i understand it.

the network adress is always divided. the lowest is the network adress, the highest the broadcast adress and the rest host adresses

in a simple example: a network with a subnet mask of would have host adresses from 1 to 254, and a broadcast adress of 255.

the subnet mask is not written in your example, so we have to guess it.

since its class C, the first three octetc are already for the network (255.255.255.x) so we only need to analyze the last one. all examples use its first 3 bits for the subnet(00100000 to 11000000) so the mask is probably 11100000, or in decimal 224. making a subnet mask of

after masking the ip we only have 5 digits left for IPs, the maximum number we can express with 5 digits is 31. add the 0 and you have 32 possibilites. now the network is divided 0 -> network adress 1 -> first host 31-> broadcast

first network is 0-31. next network is 33 to 62 and 63 the broadcast etc etc.

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