quote:
Originally posted by http://en.wikipedia.org/wiki/Dynamic_IP#IP_address_allocation
IP Allocation
Dynamic allocation, the only method which provides dynamic re-use of IP addresses. A network administrator assigns a range of IP addresses to DHCP, and each client computer on the LAN has its TCP/IP software configured to request an IP address from the DHCP server when that client computer's network interface card starts up. The request-and-grant process uses a lease concept with a controllable time period. This eases the network installation procedure on the client computer side considerably
Which means that a dynamic IP adress is granted for X time by your ISP. After that time, your IP will be renewed to a different one.
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