Subnet Mask

While I wait for my book, let’s remember how to calculate a network subnet mask.

What?
If you`re new to it, this basically sets the size of the network, the subnet mask will tell how many IP addresses will be available, on IPv4 version this could be something from 1 till 4,294,967,296 (2^32).
Subnetting will break a big network into a smaller, every time you do that you will lose 2 addresses, the very first IP considered the network ID and the last IP as Broadcast address.

Why?
On a broader scale it gives better performance as your router doesn`t need to know the routing table from all the global internet, looking on a local home or enterprise network, it can increase security and performance as you can do a segmentation from different areas or devices.

How?
First you need to check how many devices you already have on same network and your growth expectation, e.g. 80 devices plus 100 for future you need a network for 180 hosts at least, once you decide for an amount of available IPs, with your IP address range it’s time for math.