All you need to know about IP address

What is IP address?
What is my IP address?
Dynamic IP address vs. static IP address
Private IP address vs. public IP address
What is the function of IP address?
How will the website I visit use my IP address?
Is there a risk from exposing my IP address to the world during an Internet connection?
How can I hide my IP address?
What is IP address version 6 and what is it for?

What is IP address?

If you aren't sure what IP address is, IP (Internet Protocol) address is a unique address that identifies a computer or a device on the Internet. It contains 32 bits or 4 bytes (octets) and is written in four sets of decimal numbers separated by a period (or dot) in between. Each set of decimal numbers represents a byte (i.e. 8 bits) and can not exceed 255, that is when all the eight bits are 1 (or 11111111). Example of IP address:

An IP address is comparable to a telephone number that uniquely identifies an individual or a business on the telephone network.

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==>> The anatomy of IP address

Every computer or device on the Internet is part of a network (e.g. ISP, corporate, or home network). That's why IP address body (i.e. where x is a decimal number) consists of network identity (ID) and host (i.e. node/device) ID. A subnet mask value which resembles an IP address is usually given along with an IP address to help identify which part of the address refers to network ID or host ID. Subnet is logical grouping of hosts in a network that functions to segregate traffic.

In a class A IP address, the first byte refers to network ID and the last three bytes refer to host ID. In a class B IP address, the first two bytes refer to network ID and the last two bytes refer to host ID. In class C IP address, the first three bytes refer to network ID and the last byte refers to host ID. Class A IP addresses are used by very big networks, class B by medium to large networks, while class C by small networks.

  From To Default subnet mask
Class A
Class B
Class C

Example, if your computer IP address is (a class C IP address), it must belong to a network (LAN) with this network address and its host ID is 3.

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What is my IP address?

Your IP address currently is

When your computer (be it a desktop PC, laptop/notebook, netbook, tablet, handheld/PDA, or smart phone) accesses the Internet, it has an IP address that is assigned to it by your ISP or a broadband router in your home or company network. IP address is different with MAC address. A MAC address or physical address was assigned to a device by its manufacturer and stays the same during its lifetime while IP address depends on the network or service provider through which your computer or device gets an Internet connection.

For example, if you use Windows XP, to check your IP address, do one of the following:

1) double-click your Internet connection icon on the taskbar and click the Details tab.
2) open the Command Prompt window and type this command : ipconfig or ipconfig /all. You can go to the Command Prompt through Start > All Programs > Accessories > Command Prompt. [To find Command Prompt in Windows Vista or Windows 7, just click Start button and type cmd in the search box and press Enter.]
3) go to Network Connections folder, click on your Internet connection name, and see your IP address on the Details pane on the bottom left of the folder. You can go to the Network Connections folder through Start > Connect To > Show all connections or through Control Panel. [In Windows Vista or Windows 7, right click a connection icon on the taskbar/system tray, select Network and Sharing Center. On the left pane, select Manage network connections to open Network Connections folder. Right click an active connection, select Status, and click Details.]

This article provides a more detailed interpretation of your IP address.

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Dynamic IP address vs. static IP address

When your computer connects to your ISP, your ISP assigns an IP address to it. In the case of dial-up access over telephone line or broadband access (e.g. DSL or cable modem) using PPPoE/PPPoA that requires log-in, your computer will get a different IP address each time it connects to the ISP and makes an Internet connection through it. This address is called dynamic IP address. The IP address is assigned by a DHCP server at your ISP. This this the most common case since every ISP has limited IP addresses stock. On the other hand, using an always-on broadband connection, your computer is usually given the same IP address all the time by the ISP. This address is called static IP address.

Dynamic IP address is assigned to your computer by a broadband router (or residential gateway) if your computer is on a LAN (home or office network) and accesses the Internet through a broadband router. But this address is for internal use only, it gets converted to a public IP address when communicating over the Internet. Dynamic IP address assignment is handled by a DHCP server at the router. The DHCP server can be set to reserve an IP address for a computer during a connection or change it periodically at a predefined interval. The router also handles the network address translation (NAT), i.e. converting private IP address assigned by the DHCP to a public IP address assigned by the ISP.

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