BT 2-Wire Business Hub handing out wrong IP Address

One of our clients had a hard drive crash that prevented them booting into Windows.  As the machine was pretty old, and running XP, we agreed that it was a good time to upgrade to Windows 8 and snappy new hardware.

Everything went well, we managed to reinstall all of the software on the new machine, and transfer over all of the data.  We even managed to make a VHD image of the old broken hard drive, and copy that onto the new machine.

As the machine was the network server as well as one of the workstations, it seemed the best plan was to keep the machine name the same, so that the new machine could impersonate the old one.

The only problem was that the BT Hub was insisting on handing out the IP address of the old, dead machine (192.168.1.100) instead of the one assigned to the new machine via DHCP.  And there seemed to be no way to get the Hub to forget about the old machine.  Sometimes it returned 127.0.0.1 and others it returned 192.168.1.100, but never it seemed 192.168.1.64

This problem dragged on for a couple of weeks, until finally I noticed the problem.

The BT hub has case sensitive host names.  The old machine was STUDY, and the new machine was study.

When a lookup of a host name was requested, the old machine was first in the table, and a case insensitive comparision returned that, instead of the new lower case machine.  Why the Hub compares as case insensitive but inserts as case sensitive appears to be a bug in the firmware.

The FIX?

Simply rename the machine on the control panel to be the old upper case version.