Okay, so you know how people have different-sized homes, right? Some people live in big houses with lots of rooms, while others live in smaller houses with fewer rooms.
Similarly, computer networks have different-sized “homes” called subnets. A subnet is like a group of computers that are all connected to each other.
In the past, people used a system called “classes” to decide how big each subnet should be. This was like saying that only big families could live in big houses, and only small families could live in small houses. But sometimes, this meant that some houses were too big for the families that lived in them, and some families didn’t have enough space in their houses.
Nowadays, people use a CIDR system to decide how big each subnet should be. This is like saying that any family can live in any size house, as long as it’s the right size.
CIDR uses a special way of writing down how big each subnet is, called the “/n” notation. The “n” tells you how many computers can be in the subnet. For example, if the notation is “/24”, it means that there can be up to 256 computers in the subnet.
CIDR is better than the old system because it allows people to use subnets that are just the right size for their needs, without wasting space. It’s like making sure that every family has the right size house for them!