Why doesn't my computer work on the network anymore after it returned from the repair shop?

Last revision September 27, 2005

The unique network identity for any computer, printer, or other device connected to the network is its "ethernet hardware address", sometimes also called "physical address" or "MAC address" (stands for Media Access Controller). This number, burned in read-only memory in the computer (or ethernet adapter, if it is separate) is unique in all the world. So, when you register your computer, this is the most important piece of information. It is then used by the campus servers to recognize you as a valid registered computer and to provide you an IP address via DHCP.

On most modern computers, the ethernet adapter is integrated into the motherboard and the ethernet hardware address is burned into ROM on the motherboard. If you send your computer in to be repaired, and they have to replace the motherboard, you will end up with a new ethernet hardware address. Now the campus DHCP servers no longer recognize your computer and will not provide it with the IP address and other configuration information needed to function on the network.

The solution to this problem is to send the new ethernet hardware address to the network manager, so he can update your campus network registration. Of course, you must also tell him the network name or IP address assigned to your computer so he can find its record in the database!

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