1) An IP address is an identifier that is assigned at the Internet layer to an interface or a set of interfaces. Each IP address can identify the source or destination of IP packets.

2) 2 types of IP address :

* Public IP address

Public IP Addresses (also known as Static IP Addresses) are IP addresses that are visible to the public.Because these ip addresses are public, they allow other people to know about and access your computer, like a Web server.

* Private IP address

These addresses can be used on a private network, but they’re not routable through the public Internet. This not only creates a measure of much-needed security, but it also conveniently saves valuable IP address space.

RFC 1918 defines the following address prefixes for the private address space:

*

10.0.0.0/8 (10.0.0.0, 255.0.0.0)

Allows the following range of valid IPv4 unicast addresses: 10.0.0.1 to 10.255.255.254. The 10.0.0.0/8 address prefix has 24 host bits that you can use for any addressing scheme within a private organization.
*

172.16.0.0/12 (172.16.0.0, 255.240.0.0)

Allows the following range of valid IPv4 unicast addresses: 172.16.0.1 to 172.31.255.254. The 172.16.0.0/12 address prefix has 20 host bits that you can use for any addressing scheme within a private organization.
*

192.168.0.0/16 (192.168.0.0, 255.255.0.0)

Allows the following range of valid IPv4 unicast addresses: 192.168.0.1 to 192.168.255.254. The 192.168.0.0/16 address prefix has 16 host bits that you can use for any addressing scheme within a private organization.



3) Example of IP address :

The IPv4 address 11000000101010000000001100011000 is expressed as 192.168.3.24 in dotted decimal notation. To convert an IPv4 address from binary notation to dotted decimal notation, you:

*

Segment it into 8-bit blocks: 11000000 10101000 00000011 00011000
*

Convert each block to decimal: 192 168 3 24
*

Separate the blocks with periods: 192.168.3.24

For more information, please visit at http://technet.microsoft.com/en-us/library/bb726995.aspx