IP Addresses and Domain Names
Computers connected to the Internet must speak the "Internet language" called the "Internet Protocol" or simply "IP." Each computer is assigned a unique address somewhat similar to a street address or telephone number. Under the current system there are four numbers that range from 0 to 255 (Example: 206.156.18.122). Every computer, whether it functions as a web site, is being used by a web surfer, is a mail server, and/or is used for any other function, has an IP address so it can communicate across the Internet. Communication is accomplished by sending pieces of information called "packets" that include the IP address of the destination computer.
How are IP Addresses Distributed?
Every transfer of information over the Internet must include the capture of the IP address. Some examples of automatic logging are: visiting a web site, sending or receiving e-mail, using a chat room, or reading and posting to newsgroups. A common situation that causes IP addresses to be distributed to a third party is when visiting a web site and that site participates in banner ad networks where the ads are served from a third party site. This third party site retrieves the IP address when it sends the ad. This information is used to measure the number of ad views and calculate click-through rates.
Transferring IP addresses to a third party can also be accomplished by sending a web page via e-mail. When the user opens the attachment (if they are connected to the Internet) the e-mailed web page could make a request to a web site anywhere on the Internet (such as requesting an image file). This transfers the user's IP address to that web site along with the date and time that the user opened the message. An Internet cookie can also be placed on the user's system at that time. Several advertisers already engage in this practice. This method could also be used to defeat anonymous e-mail.