I was studying TCP/IP and wanted to know why is subnetting so advantageous?

Question

javk · Answer

I think it's something to do with decreasing the amount of data traffic on the network

anonymous · Answer

Well, from what I know, if a computer needs to send an IP message to another device it will check if the destination IP address is within the same subnet as its own.
In case it is in the same subnet then the computer will send the message directly to the destination device if possible.
If they are not in the same subnet then it will try and send it through the Gateway. The message sent to the gateway will then passed on until it'll get to the destination. If no such Gateway device configured then the transmission will simply fail.
So by making devices be in the same subnet you allow them to communicate directly without going through the Gateway.

You can make a small experiment. Take two computers and plug them together with an ethernet cable. Now manually configure their IP preferences such as their IP addresses, subnets and gateways.
First time, configure them to be in the same subnet, without any gateway. Try to ping, it should work.
Second time, configure them not to be in the same subnet, still without any gatway. Now the ping shouldn't work.
Third time, configure them not to be in the same subnet, but configure each one to be its own gateway (same gateway address as its IP address). Now the ping should work again.
You can also connect them both to a router, for example, and set it to be their gateway, it should also work. The computers will pass the message to the gateway and it will pass it on, without caring about subnet anymore.

e.mccormick · Answer

Lets say I wanted to assign you an IP so you could get on the internet.  Now, should I assign you a class A, class B, or class C network?  Well, none of those.  Subnetting lets you assign less space or even individual IPs to get a person on the internet.  That is one use.

Subnets are also useful for organizing things.  Say put all people that are in one workgroup on a subnet that shares access to the resoueces they need.