Originally Posted by
Maq-
If your ISP assigns your IP via DHCP, there's a lease time accompanying that IP. Meaning, for a certain amount of time, no matter what, your line will control that IP address.
Now, locally (if your router assigns IPs via DHCP to your local network) you can simply release the lease, and your router will look for the next IP to assign when you start the computer back up, or attempt to repair the connection. But, this won't change your public IP address at all.
If your router has an option to release the IP, this could work, but only if no-one else new to the network is assigned that IP in the time you have your router/modem off.
If not, when you power it back up, the DHCP server will simply give you the old IP again.