Hi Lifehacker, For some reason whenever I look at a network "subnet" I just can't figure it out. I understand that the subnet is broken into 8 bits (so 255.255.255.0 would give me 254 addresses). But why? How do I then convert something like 18.104.22.168/12 to get an idea of what the subnet mask would be and how many addresses I would get? Thanks, Net Getting It
Subnet picture from Shutterstock
There are really a couple of separate issues to address in your question. Let's start with the first part – why does a subnet of 255.255.255.0 give you 254 addresses?
This is the way TCP/IP is designed. When devices on a network are in the same subnet, then they are deemed to be on the same segment of a larger network. Even if two devices have the valid network addresses, they won't be able to communicate unless they're in the same subnet.
Your second question is "How do I then convert something like 22.214.171.124/12 to get an idea of what the subnet mask would be and how many addresses I would get?"
There's a useful article at TechRepublic that explains how subnetting works and how many addresses you get.
As far as we can tell, you can’t calculate the subnet from the address although we're far from networking experts and would gladly be corrected by someone in the Lifehacker family.
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