This problem struck me yesterday, and after much Googleing (including many great posts on this site) I finally figured out what was causing this in my case. I present so that maybe it might help someone with this particular version of the problem.
Yesterday while I was busy working (OK, playing Freecell), the neighborhood power went out. When restored, my main desktop machine could not get on the internet. All other machines in the house were fine, so I was 95% sure it was the desktop.
The Network and Sharing Center was telling me that I was connected to an unknown public network. The network troubleshooter isolated the problem to Local area connection doesnt have a valid IP configuration
From the results of Google searches, I tried netsh resets, driver updates, Windows system restores, unplugging the machine, and I wish I had a nickel for each IPCONFIG /ALL.
The first main clue was the IP address 169.254.186.7 or something close. THAT was the invalid IP address.
From what Ive learned, if its starts with 169 istead of 192, then the computer isnt getting an IP address from the router. Windows assigns the 169 address in cases like this. Now, why was that ?
In one of those classic what made me look for that moments, I noticed the MAC address of my NIC was all zeros. My theory is that when the DHCP request goes out with an all zeroes address, the router ignores it. Or maybe with all zeros, Windows doesnt bother. At any rate MAC=0 mean no IP address.
The all zeros address shows up in IPCONFIG /ALL and the NIC properties.
Why would there be an all zeros address? Well, that I never figured out. I suspect the power glitch did a minor fry job on the embedded NIC on my motherboard. But I DID learn that Windows can override the onboard NIC value. http://digitalpbk.com/windows/change...ress-windows-7
WOO HOO! I assigned a MAC address (12 characters 0 thru F), and that cleared everything up.
So MAC address all zeros assign your own network restored.
I'm up and running (this post from my repaired machine). If anyone has some ideas about why the MAC address zeroed out, I'd be interested in hearing.
Yesterday while I was busy working (OK, playing Freecell), the neighborhood power went out. When restored, my main desktop machine could not get on the internet. All other machines in the house were fine, so I was 95% sure it was the desktop.
The Network and Sharing Center was telling me that I was connected to an unknown public network. The network troubleshooter isolated the problem to Local area connection doesnt have a valid IP configuration
From the results of Google searches, I tried netsh resets, driver updates, Windows system restores, unplugging the machine, and I wish I had a nickel for each IPCONFIG /ALL.
The first main clue was the IP address 169.254.186.7 or something close. THAT was the invalid IP address.
From what Ive learned, if its starts with 169 istead of 192, then the computer isnt getting an IP address from the router. Windows assigns the 169 address in cases like this. Now, why was that ?
In one of those classic what made me look for that moments, I noticed the MAC address of my NIC was all zeros. My theory is that when the DHCP request goes out with an all zeroes address, the router ignores it. Or maybe with all zeros, Windows doesnt bother. At any rate MAC=0 mean no IP address.
The all zeros address shows up in IPCONFIG /ALL and the NIC properties.
Why would there be an all zeros address? Well, that I never figured out. I suspect the power glitch did a minor fry job on the embedded NIC on my motherboard. But I DID learn that Windows can override the onboard NIC value. http://digitalpbk.com/windows/change...ress-windows-7
WOO HOO! I assigned a MAC address (12 characters 0 thru F), and that cleared everything up.
So MAC address all zeros assign your own network restored.
I'm up and running (this post from my repaired machine). If anyone has some ideas about why the MAC address zeroed out, I'd be interested in hearing.