IP Address

IP addresses are broken into 4 octet (IPV4) separated by dotted decimal notation.An octet is a byte consisting of 8 bits. There are two parts of an IP address:

1. Network ID
2. Host ID

The various classes of networks specify additional and fewer octet to designate the network ID versus host ID

Class A-E Networks
The addressing scheme for class A through E network is shown below.

There are some network addresses reserved for private use. There are three sets of addresses reserved:

1. 10.x.x.x
2. 172.16.x.x. - 172.31.x.x
3. 192.168.x.x

Other reserved or commonly used  addresses:

1. 127.0.0.1 - The loopback interface address. All 127.x.x.x address are used by the loopback interface
2. 0.0.0.0 - Thi is reserved for host that do not know their address and and use BOOTP or DHCP protocols to determine their addresses 
3. 255 - The value of 255 is never used as an address for any part of IP address. It is reserved for broadcasting address .