Quote Originally Posted by nishtya
... There is something wrong here. Thoughts?
It's a router issue. Some routers have a way to lock an IP address to a MAC address, so when you reboot DHCP still hands out the same address each time. I believe Dlink is one that has this. Without this feature, it can be a real pain, not just with Knoppix and Linux, but even if you are just using Windows and want to forward ports to certain computers. You can check the docs for your particular router (but I'm guessing you already did that). Otherwise, complain to the manufacturer or buy a router that lets you dedicate an IP address by MAC (and still lets you use DHCP to give them out).

In addition to Dlink, which does it right by a configuration item, SMC seems to almost get it right - it seems to always hand out the same IP address to the same MAC address (if it is still available). The down sides are that for no obvious reason SMC does not assign IP addresses from the IP pool in any obvious order, if you change the size of the pool all bets are off and new IP addresses will be assigned, and since there is no actual coonfiguration item to set this up you can never be sure it will keep working.