Was talking to one of the IT guys at work today and he mentioned that he had to work on something called a subnet. I tried Googling it but found myself even more confused on its definition.
In: Technology
Before a computer goes to send network traffic it checks the destination address against its own address. If the computer has a subnet mask of 255.255.255.0 then it will check the first 24 bits of its address against the first 24 bits of the destination address. (Remember 8 bits in a byte and if all 8 bits equal “1” then the value is 255).
If those first 24 bits (in this example) of both addresses match then the source knows that it’s target is on the same “subnet” and it can speak directly to it. If the first 24 bits do not match, then the source knows that it must send the traffic to a different subnet (or really “network”) and therefore the traffic must be sent to a router first in order to be sent on to its destination. If there is no router (AKA gateway) then you’re out of luck!
Hypothetically all IP addresses could exist across one single, flat, giant network with no rules. This would lead to total chaos however by allowing anyone to talk to anyone no matter what. By breaking the total number of available addresses into smaller blocks (subnets) it becomes easier to apply security rules and to send traffic only to the place where it is required.
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