ITD ::: All you need to know about IP address

All you need to know about IP address

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: 202.60.80.1
An IP address is comparable to a telephone number that uniquely identifies an individual or a business on the telephone network.

==>> 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. xxx.xxx.xxx.xxx 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.
 Example, if your computer IP address is 192.168.1.3 (a class C IP address), it must belong to a network (LAN) with this network address 192.168.1.0 and its host ID is 3.

What is my IP address?

Your IP address currently is 119.73.71.173
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.]

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.

Private IP address vs. public IP address

Private IP address is only used within a LAN or an internal network (e.g. home or company network), while public IP address is used for communication over the Internet. If your computer is part of a company network, chances are it is assigned a private IP address and when it connects to the Internet the private IP address is translated to a public IP address by a router which has NAT capability. Private IP address is also known as internal IP address, while public IP address is external IP address. LAN IP address is always a private IP address, while WAN IP address can be a private or public IP address. This article clarifies the difference between LAN IP address and WAN IP address.
OK, in case you are wondering, the table below tells you which IP addresses are allocated for use only in internal networks as private IP addresses.

What is the function of IP address?

IP addresses are used by devices called routers on the Internet to forward messages from one computer to another over the Internet. In comparison to a telephone network, a router acts like a telephone switch (exchange) that connects a caller to the dialed phone number.
When you send a message over the Internet, the message is broken down into small pieces - called packets - where each packet can take its own route. IP addresses information is included in the packet header. Your computer sends each packet along with your computer (i.e. source) IP address and the receiving computer (i.e. destination) IP address. The routers read the source and the destination IP addresses by examining a packet header and forward the packet accordingly.
However, you usually type a web address (e.g. www.conniq.com) instead of an IP address in your browser's address bar. That's because there are servers on the Internet that store the mapping of web addresses to IP addresses. They are called DNS servers. The DNS servers handle the translation from a web address to an IP address. A DNS server is analogous to a telephone directory that contains a list of telephone numbers and businesses or individuals who own the numbers.

==>> How many routers do forward my message before arriving at a specific web address?

Your message does not get to the destination address via one router. There are many routers involved in forwarding your message to the destination computer (i.e. in this case, a web server). You can do little investigation by typing tracert ip_address or tracert web_address in Command Prompt. Replace the ip_address or web_address part after tracert with your destination, e.g. www.myexampledestination.com. This command will trace the routes that take your message to its destination by sending ICMP messages. Some routers have been set not to accept an ICMP message from the Internet therefore you won't get a reply. But since many allow it, by reading the result you would be amazed at how far your message can travel in milliseconds and how many hops it makes to get to its destination.

How will the website I visit use my IP address?

Your IP address can be used for location targeting that is identifying where you come from and presenting you relevant content tied to your geographic location. That's because IP addresses in bulk are allocated to regions and countries around the world by the IANA in a delegated manner through several Regional Internet Registries. And each ISP obtains IP addresses for its subscribers from Local or National Internet Registry.
Nonetheless, a website you visit can not know who you are, solely from your IP address. Unless you register to the website and gives it your personal information, you will remain anonymous.