Windows – “the dns server is not a valid ip address” error

Rather than using a .reg file you can use the NETSH command line util, e.g.

netsh interface ip set dns "Local Area Connection" static 192.168.0.200

taken from and more info available here

You can then create .bat files with the 2 different settings you want

You want to a use a tool called nslookup. This is command-line tool that is included with Windows, so you already have it. Just open a command prompt, type nslookup, and press enter. Then you can start entering names to resolve. You can change the server it checks against by type "server x.x.x.x", where x.x.x.x is the IP of the new server. Type "quit" when finished.

The other thing I would check is IPv6. You may have a dns server that's returning IPv6 addresses, or a machine that is sending out IPv6 address requests, and then a browser that only knows IPv4 routes to the web.

After that, if and only if you still haven't found the problem, you can try a reset of your ip stack. From a command prompt:

netsh int ip reset resetlog.txt