There are two types of ip address. 1.static ip 2.dynamic ip. Static Ip-address: Static Ip-address will not change if you refresh the modem or switch off and on the modem again.It's remains same. Dynamic Ip-address: Dynamic Ip-address will change whenever you refresh the modem a new ip allocated for you...... If you need your computer ip do the following instructions For Windows xp 1.start->Run 2.cmd 3.Type ipconfig 4.press enter You can find your external ip address using any one of the online site .Recently i checked my ip address using ip-details.com