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Originally Posted by Tay
A MAC address is supposed to be a unique HARDWARE based serial number of your network card. It consists of 12 digits usually seperated by dots. eg: A0.12.23.34.45.56. You cannot change the physical address of this card, it is possible however, to spoof (Disguise) the MAC address, but this is another story.
It would seem however that MAC address is a red herring as has been stated. XP appears unable to detect the MAC address. If you are getting a DHCP server assisgned "Valid" IP address then the mechanism is working (Simply that XP is unwilling to show it).
The negotiation process for an IP is pretty straight forward In basic terms, Your PC is setup for DHCP client, when you power on it sends a broadcast out on to the network and a DHCP server should respond, it then assigns you an IP address that is then linked (Virtually) to your MAC address. hey presto you have an IP address. You are leased the IP address only, after a certain time the IP address can be renegotiated for or the DHCP server releases it to be used by somebody else.
If your connection is dropping and you keep the same IP address when it restarts, then I suspect that it is not the DHCP negotiation process but something external, cables, cable service, something overheating, PC, software etc.
If you are losing the IP address then it may be that your service is physically stopping OR your lease has run out and is unable to renegotiate with the DHCP server to keep the existing address.
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Good explanation. Just to expand - in the case of the NTL setup, NTL provide the DHCP server, and addresses are leased for quite a time (don't quote me, but two weeks rings a bell). After a percentage (I think it is 50%) of this time, if you are connected, or the next time you connect, the lease is renewed for a further period (two weeks?). It is because of this mechanism that your NTL-assigned IP address, although theoretically dynamic, rarely changes. In this case, the mystery is a) why does the PC NIC MAC address show up as zeros? and b) how does ANY connection occur? Can DHCP allocate an IP address to an all-zeroes MAC address, and, if so, could this be causing a problem, e.g if there are other all-zero MAC addresses on the NTL network?
As noted earlier, it is possible to 'spoof' the MAC address on some, if not all, cards (e.g. - on Windows 2000 at least - Network Connections, right-click on connection, select card properties, advanced, 'locally-administered address'). Could it be that a virus or some such has changed this 'software' address?