IP Basic Address Structure and Main Components
As I mentioned in the IP addressing overview, one of the ways that IP addresses are used is to facilitate the routing of datagrams in an IP internetwork. This is made possible because of the way that IP addresses are structured and how that structure is interpreted by network routers.
Network ID and Host ID
As you just saw, each IPv4 address is 32 bits long. When you refer to the IP address, you use a dotted decimal notation, while the computer converts this into binary. However, even though these sets of 32 bits are considered a single entity, they have an internal structure containing two components:
Network Identifier (Network ID) A certain number of bits, starting from the leftmost bit, is used to ...