How Does a Website Detect a Computer's IP Address?

Assigning an IP Address

When you connect to the Internet from a computer, your system communicates with the network through an IP address. Most Internet providers automatically assign IP addresses to computers, and that unique number is used to identify your computer. IP addresses consist of four three-digit numbers, separated by periods. In certain situations, you may need to assign a static IP address to your computer instead of obtaining one automatically from your Internet provider.

Connecting to the Internet

Although IP addresses are assigned to personal computers, they are also given out to all websites. The web address that you use to access your favorite websites is just a symbol for the site's IP address. Your IP address begins communicating with the Internet when you open a web browser and connect to a new site. Data travel from your computer to your network's router before connecting to other websites on the Internet.

Detecting IP Addresses

When your computer communicates with a website through a browser, packets of data are being transferred between the two systems' IP addresses. These data packets are sent back and forth continuously, so the website you are visiting can see what IP addresses are contacting the site. After detecting your IP address, the website can also see what Internet provider you are using and even the general location of where your connection is coming from.

Tracing an IP Path

Using any command-line prompt, you can trace the route of your Internet connection to any website and see where the data are traveling. The trace route command shows you the network path that your computer follows and all of the other IP addresses it encounters.