[N3WBI3]

The reason ISP's use DHCP (Dynamic IP) is so that they can make changes like install a new DNS (server which turns freerepublic.com into an IP address) Server without the client haivng to change anything every time you attach you get an address, DNS servers, and other information..

[js1138]

I would think the main reason for a dynamic IP is to increase the number of available connections. Don't they use address translation, and wouldn't this hide the PCs IP from outsiders? I suppose this depends on the type of service.