I'm a PC technician and we run a network here in the store through Adelphia cable. The cable modem connects directly to a WinXP Pro (SP2) machine and we share the connection via a 2nd NIC. After that, we go through a couple switches and throughout my workspace. Now, being a technician, I see a great deal of PC's (around 100 per month). Each one gets connected to the internet at one point or another through the switch. For PCs that aren't equipped with ethernet, I'll use a USB Ethernet adapter. Now here's whats happening:
Starting a couple of weeks ago, I started noticing that the customer's PC's were not acquiring an IP address from the DHCP. Instead they were given the dreaded Automatic Private IP Address. Because of this, they weren't able to connect to the internet, which is a serious problem. It slowly seemed to get worse and worse. Now, two weeks later, any PC that comes in a can NOT acquire an IP address from the DHCP and I always get (limited or no connectivity). The only PC's that work on the network are the ones that have been here for awhile. Now, the reason I suspect MAC address problems is because while none of the "fresh" PC's that come in will acquire an IP, I can plug in the USB Ethernet that I've been using for over 6 months now and it will work! I'm guessing that no matter what PC the USB Ethernet (Netgear FA120) is connected to, it retains the same MAC Address and therefore the Server (our WinXP Pro machine) recognises it as an old one and will easily give it an IP. However, any new ones that come in that it's never seen before it will just go into meltdown as it tries to acquire an for about 30 seconds then finally gives up and says "Limited or No Connectivity, unable to retrieve IP address", gives me an Automatic Private Adress, and the Internet doesn't work.
Now, most people will be quick to say "how do you know its not the ethernet in the PCs or the cabling?". Well, I know its not the ethernet because when I configure the TCP/IP settings manually, I can sucessfully ping the gateway and see all the other PC's on the network. I just can't access the Internet. Also, I have tried playing with the "net config server /autodisconnect" command and it doesn't help at all.
So, for anyone that has actually read all this, what I'm asking is if its possible for a MAC address list to fill up in Windows XP Pro? Because right now, the only NIC's that connect to the internet are the one's that were working prior to two weeks ago. If it is possible, how do you purge the list and start over (short of reformatting). Thanks for any help.