I am running window 7 and after the windows Tuesday updates, I had some issues.
Running Firefox, I noticed that some web pages were not resolving, and some were. I have a wireless connection with DNS settings to OpenDNS servers. I also have a wired connection with DNS settings to Google DNS servers.
after the updates from Tuesday, is when the issue started happening. Immediately, I could tell that my other PC was still working using default DNS settings from my ISP. So knowing my set up, it was easy to disable the wired network to test what was going on.
With the wired network disconnected, everything started to work just fine.
When I reconnected the wired network some sites failed.
I then changed the DNS setting on the wired network, to prove that the issue was DNS or the wired network.
once the changes took effect, everything started to work just fine.
So now I am at the state of two networks, one wired and one wireless, both using Open DNS. and all systems are green.
I then disabled the wireless network, and put the DNS settings back to Google DNS servers.
This worked, but I don’t know why.
I was able to recreate this after restarting the machine again.
So in the end I am not sure what I have learned. I have had my set up like this for years.