From the course: Learning Subnetting

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Calculating available hosts

Calculating available hosts

From the course: Learning Subnetting

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Calculating available hosts

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- [Instructor] In our previous video we saw that if we added some bits to the natural or the default subnet mask, that we could take that one network and carve it up into multiple networks. We added three bits to the natural mask and we created eight subnets as a result. But the question that follows is, now that I've got a certain number of subnets that have been created, how many hosts, in other words, how many assignable IP addresses do I have for each of those subnets? And the formula to determine that is two raised to the power of h, minus two where h is the number of host bits that remain in that subnet mask. And before we go through a mathematical example, let's answer the obvious question, why are we subtracting two? Why can we not just say two to the h? Well, remember that within a network there's a couple of IP addresses that we cannot assign to a device. There's the network address. That's where all…

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