What is ip & what is public & private ip?

nternet Protocol (IP) addresses are
usually of two types: Public and Private. If you have ever wondered to know
what is the difference between a public and a private IP address, then you are
at the right place. In this post I will try to explain the difference between a
public and a private IP addres in layman’s terms so that it becomes simple and
easy to understand.



What are Public IP Addresses?





A public IP address is assigned to every computer that connects to the Internet
where each IP is unique. Hence there cannot exist two computers with the same
public IP address all over the Internet. This addressing scheme makes it
possible for the computers to “find each other” online and exchange
information. User has no control over the IP address (public) that is assigned
to the computer. The public IP address is assigned to the computer by the
Internet Service Provider as soon as the computer is connected to the Internet
gateway.



A public IP address can be either static or dynamic. A static public IP address
does not change and is used primarily for hosting webpages or services on the
Internet. On the other hand a dynamic public IP address is chosen from a pool
of available addresses and changes each time one connects to the Internet. Most
Internet users will only have a dynamic IP assigned to their computer which
goes off when the computer is disconnected from the Internet. Thus when it is
re-connected it gets a new IP.

You can check your public IP address by visiting www.whatismyip.com



What are Private IP Addresses?



An IP address is considered private if the IP number falls within one of the IP
address ranges reserved for private networks such as a Local Area Network
(LAN). The Internet Assigned Numbers Authority (IANA) has reserved the
following three blocks of the IP address space for private networks (local
networks):



10.0.0.0 – 10.255.255.255 (Total Addresses:
16,777,216)

172.16.0.0 – 172.31.255.255 (Total Addresses:
1,048,576)

192.168.0.0 – 192.168.255.255 (Total
Addresses: 65,536)



Private IP addresses are used for numbering the computers in a private network
including home, school and business LANs in airports and hotels which makes it
possible for the computers in the network to communicate with each other. Say
for example, if a network X consists of 10 computers each of them can be given
an IP starting from 192.168.1.1 to 192.168.1.10. Unlike the public IP, the administrator
of the private network is free to assign an IP address of his own choice
(provided the IP number falls in the private IP address range as mentioned
above).



Devices with private IP addresses cannot connect directly to the Internet.
Likewise, computers outside the local network cannot connect directly to a
device with a private IP. It is possible to interconnect two private networks
with the help of a router or a similar device that supports Network Address Translation.



If the private network is connected to the Internet (through an Internet
connection via ISP) then each computer will have a private IP as well as a
public IP. Private IP is used for communication within the network where as the
public IP is used for communication over the Internet. Most Internet users with
a DSL/ADSL connection will have both a private as well as a public IP.



You can know your private IP by typing ipconfig command in the command prompt.
The number that you see against “IPV4 Address:” is your private IP which in
most cases will be 192.168.1.1 or 192.168.1.2. Unlike the public IP, private IP
addresses are always static in nature.



Unlike what most people assume, a private IP is neither the one which is
impossible to trace (just like the private telephone number) nor the one
reserved for stealth Internet usage. In reality there is no public IP address
that is impossible to trace since the protocol itself is designed for
transparency.