About Ip Addresses..................

Do you know about IP addresses?

In daily life we hear the word IP address. Generally we might get a question like what is IP address. How its implemented? How to find/know system ip? Here I am planning to share about the system Ip address.

What's an IP address ?

IP (Internet Protocol) address is a unique 32 bit number assigned to each machine connected to the Internet (or an IP network), either permanently or temporarily (by dial up connection or similar).
A typical IP address looks like - 207.153.234.217

How to find IP Address of My system?

The systems which are connected to internet will have an IP address. To know about your system IP addresses go to command prompt and type a command “ipconfig”, This will display the below information. So IP Address of this system is 115.241.3.171.
 Connection-specific DNS Suffix  . :
        IP Address. . . . . . . . . . . . : 115.241.3.171
        Subnet Mask . . . . . . . . . . . : 255.255.255.255
        Default Gateway . . . . . . . . . : 115.241.3.171

Do you want to know more about IP Address?

IP addresses are usually denoted as 4 decimal numbers (also called octets), separated by dots. This format of representing an IP address is known as "dotted quad" or "dotted decimal" notation. (There are also base 10 notations, but it is rather uncommon). Each octect is represented in binary format by a single byte or 8 bits, thus 4 octets form a 32 bit IP address as shown above. (Note: This is valid for IP version 4 only). Theoretically, 32 bit IP addresses can accommodate almost 232 = 4,294,967,296 (approximately 4.3 billion) machines on an IP network, such as Internet. In reality however, the number is much less than this number because many IP address ranges are reserved for special purpose and should not be used for another purpose.

What an IP address contains?

An IP address consists of two parts, one identifying the network and one identifying the node or host. Each network can have "X" number of nodes or hosts under it. In the class system, the class of the address determines which part belongs to the network address, and which part belongs to the host address. In newer CIDR (Classless Inter-Domain Routing) system, this information is specified along with the IP address itself, thus allowing more efficient and practical allocation of IP addresses.

IP addresses have been classified into 5 classes and special purpose addresses, depending upon the value in the first octet. Viz-
Class A - This is a class for very large networks, such as IBM which holds IP addresses in the range - 9.0.0.0 - 9.255.255.255. (almost 16,777,216 IP addresses).
First Octet - - The first octet is between 1 to 126. (Starts with binary bit - 0).
Network Address - The n/w address is denoted by first 8 bits or first octet.
Host/Node Address - Host address is denoted by last 24 bits or last 3 octets.
This Network-Host IP configuration for class A can be shown as -
network.host.host.host
and each can have 1 to 3 decimals. Thus forming 126 network addresses (27 - 1) and each of them capable of having 16,777,214 (224 -2) host addresses. 

Class B - This is a class for medium-sized networks.
First Octet - - The first octet is between 128 to 191. (Starts with binary bits - 10).
Network Address - The n/w address is denoted by first 16 bits or first 2 octets.
Host/Node Address - Host address is denoted by last 16 bits or last 2 octets.
This Network-Host IP configuration for class B can be shown as -
network.network.host.host
and each can have 1 to 3 decimals. Thus forming 16,384 network addresses (214) and each of them capable of having 65,534 (216 -2) host addresses. 

Class C - This is a class for small-sized networks.
First Octet - - The first octet is between 192 to 223. (Starts with binary bits - 110).
Network Address - The n/w address is denoted by first 24 bits or first 3 octets.
Host/Node Address - Host address is denoted by last 8 bits or last octet.
This Network-Host IP configuration for class C can be shown as -
network.network.network.host
and each can have 1 to 3 decimals. Thus forming 2,097,152 network addresses (221) and each of them capable of having 254 (28 -2) host addresses. 

Class D - This is a class meant for multicasting only, for sending multicast messages to other groups of host machines.
First Octet - - The first octet is between 224 to 239. (Starts with binary bits - 1110).
The class D is a special purpose reserved class, and addresses in this range are not assigned as IP addresses on an IP network, including Internet. 

Class E - This is a class meant for experimental purpose only.
First Octet - - The first octet is between 240 to 255. (Starts with binary bits - 1111).
The class E is also a special purpose reserved class, and addresses in this range are not assigned as IP addresses on an IP network, including Internet. The IP address 255.255.255.255 in this range is also known as Broadcast.

How the IP Address allocation will be done?

Loopback:
Addresses 127.0.0.0 to 127.255.255.255 are reserved for loopback, for internal testing on a local machine. 127.0.0.1 typically refers to your own local machine, you can test this - you should always be able to ping 127.0.0.1, irrespective of connectivity to the network, as it represents your own machine.
IP addresses in this range are never valid Internet addresses.

Private Networks:
There are 3 IP network addresses reserved for private networks.
10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
They may be used by anyone setting up internal IP networks, such as organization LAN behind a proxy server or a router. It is recommended to use them because routers on the Internet should (and will) never forward packets coming from these addresses. These addresses are meaningful only for the network to which they belong (Intranet). Due to this, two or more organizations may have same IP address falling in this range assigned to two or more individual machines without any conflict.