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Total Host and Usable Host

From the text on the previous tutorial, we conclude that we have a total of 256 IP addresses. How did we come to this number?
You notice that there are 8 host bits in the fourth octet (byte), with respect to the base of the binary system 'number 2', which power on 8 host bits get it 2^8=256 total IP.
 
Here we must bear in mind that the first and last IP addresses are not usable, because the first IP address indicates the network and the last IP address is a broadcast IP address. So 256-2=54 usable IP addresses. Do not forget your computer works with Bits.

Thus, for example. 
If the B class, power 'base 2' of the number of host bits, we get the results of 2^16=65,534.
This means that on a network that has an IP address of 128.0.0.0, we are able to network 65,534 computers (ie. We have so many usable IP address), so that each computer gets an IP address and that none of them duplicates. See Figure4

Figure 4.

Usable Host of IP addresses

I hope you understand which parts of the IP addresses of the network and which bits are host.
This is important because of further division of IP addresses in a subnet.
Let's go to the next page tutorial.