How do websites such as Digg ban Ip addresses, when users on a network may be on a network that supports NAT translation? I ask because my Digg account was banned a long time ago, and I simply just signed back up again. But others say that your IP is banned, and they have trouble signing back up. So how would they do that if I'm behind a NATed network?
first off, I do not condone getting around IP blocks. I am stating this information to explain what is going on. On a home network you get one external IP address which is translated into multiple internal addresses. Internal addresses will be 192.168.x.x (x = 0-255), 10.x.x.x, or 172.16.x.x-172.31.x.x. When you change your internal address the outside world does not see the change, its only seen internally. To change the external address you have to obtain a new external IP address. Often this happens automatically if you do not pay for a static address (one that does not change). If you do not pay for a static then it is dynamic and can change. Often it does not change, especially with cable providers. To change the address quite often all that is needed is to unplug your modem for a a bit of time and then plug it back in. The amount of time will vary, you can try for just a few seconds and move up to longer. If you unplug it overnight odds are you will recieve a new external IP. There are no guarantees, but it is very likely to happen. You can check your current IP at http://ipchicken.com or even better http://www.moanmyip.com/ which might not be safe for work. Funny, but not safe for some places.
Zac's got it completely right. I wouldn't recommend going around an IP block, but sometimes you can get around it without even realizing it.