SUB NETWORKS
Introduction:-
With available IP network numbers rapidly becoming an endangered species, efficient use of this increasingly scarce resource is important.
This document describes how to split a single IP network number up so that it can be used on several different networks.
What are subnets?
A subnet is a way of taking a single IP network address and locally splitting it up so that this single network IP address can actually be used on several interconnected local networks. Remember, a single IP network number can only be used on a single network.
The important word here is locally: as far as the world outside the machines and physical networks covered by the sub-netted IP network are concerned, nothing whatsoever has changed - it is still just a single IP network. This is important - sub-networking is a local configuration and is invisible to the rest of the world.
DEFINATION:-A sub network, or subnet, is a logically visible subdivision of an IP network. The practice of dividing a single network into two or more networks is called subnet ting and the networks created are called sub networks or subnets.
All computers that belong to a subnet are addressed with a common, identical, most-significant bit-group in their IP address. This results in the logical division of an IP address into two fields, a network or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific "host" — either a computer, or a device, or specific network interface on a computer or device.
The routing prefix is expressed in CIDR notation. It is written as the first address of a network, followed by a slash character (/), followed by the bit-length of the prefix. For example, 192.168.1.0/24 is the prefix of