How to determine the number of usable host IP addresses and number of available subnets per subnet

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In every subnet, the first available IP address is used for the network address, and the last available IP address is used for the broadcast address. The remaining available IP addresses are used for the hosts in the subnet. For this reason, the number of useable IP addresses is the number of available IP addresses minus 2.

Subnet Mask Prefix Number of available IP addresses per subnet Number of subnets
255.255.255.255 /32 0 16,777,216
255.255.255.254 /31 2 8,388,608
255.255.255.252 /30 4 4,194,304
255.255.255.248 /29 8 2,097,152
255.255.255.240 /28 16 1,048,576
255.255.255.224 /27 32 524,288
255.255.255.192 /26 64 262,144
255.255.255.128 /25 128 131,072
255.255.255.0 /24 256 65,536
255.255.254.0 /23 512 32,768
255.255.252.0 /22 1,024 16,384
255.255.248.0 /21 2,048 8,192
255.255.240.0 /20 4,096 4,096
255.255.224.0 /19 8,192 2,048
255.255.192.0 /18 16,384 1,024
255.255.128.0 /17 32,768 512
255.255.0.0 /16 65,536 256
255.254.0.0 /15 131,072 128
255.252.0.0 /14 262,144 64
255.248.0.0 /13 524,288 32
255.240.0.0 /12 1,048,576 16
255.224.0.0 /11 2,097,152 8
255.192.0.0 /10 4,194,304 4
255.128.0.0 /9 8,388,608 2
255.0.0.0 /8 16,777,216 0

 

 

 

 



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