Subnets
Problem
Your computer wants to send to:
192.168.1.50
Should it send directly to that machine on the local network?
Or should it give the packet to a router?
It needs to know:
Is this destination part of my network?
Solution — Subnet Prefix
An address such as:
192.168.1.20/24
means the local network is:
192.168.1.0 – 192.168.1.255
So 192.168.1.50 is local, while 8.8.8.8 must go through a router.
Core idea: the prefix tells a host which IP addresses belong to its network.