Disappearing gateway

[imunro01]

We have a strange problem with gateway settings disappearing from machine.

* Checking the network adapter settings in Windows show the gateway correctly
* Running ipconfig shows no gateway listed.
* Setting the adapter to DHCP then back again resolves it
* A reboot causes it to re-occur
* We are running on a server 2003 domain
* Our gateway device is a school guardian

We have run the following registry hack to try and resolve it, however so far unsuccesfully.

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]

"ForwardBroadcasts"=dword:00000000
"IPEnableRouter"=dword:00000000
"DeadGWDetectDefault"=dword:00000000
"UseDomainNameDevolution"=dword:00000001
"EnableICMPRedirect"=dword:00000001
"DontAddDefaultGatewayDefault"=dword:00000000
"EnableSecurityFilters"=dword:00000000
"EnableDeadGWDetect"=dword:00000000

PC's appear to be running generally slowly when the gateway setting is missing.

Has anyone come across this, and if so how did you resolve it.

Cheers

Iain

[Michael]

On Windows Server 2003, open up DHCP Server > right click 'Scope Options' > 'Configure Options'. Tick 003 Router, then enter the required IP. On a Class C network, this would typically be 192.168.1.1 for example.

From a command prompt enter 'ipconfig /renew' and your IP, Subnet and Gateway should now be displayed correctly.

If you have more than one DHCP server in a domain, they must be setup the same, otherwise this could create a load of problems similar to what you're describing.

[imunro01]

Thanks for the suggestion on that. That option is already set on obth our DHCP servers.

What would be causing it to happen on machines configured with a static IP?

[Michael]

It's very interesting that the IP shows up in Windows but not the command prompt. That doesn't make sense for a start. Are all the workstations from the same image? Have you tried updating the drivers for your network adapters?

Try rebuilding the tcp/ip stack as follows

[imunro01]

The machines have various different types of hardware, and whilst most are built from a single sysprep image, with the relevant drivers installed afterwards, this is not exclusively the case.

I have tried the drivers without much success.

[Michael]

Have you tried rebuilding the tcp/ip stack?

[imunro01]

Yes - we've tried that, and it made no difference.

[Michael]

If you install Windows from new, join it to the domain and then configure a static IP is the problem still there?

[imunro01]

A bit of investigation shows that it only appears when the PC is in certain OU's in Active Directory, suggesting it could be a GP problem, however I'm no further enlightened as to what policy is causing it.

[Michael]

If you haven’t done so already, install GPMC on your server. It will give you detailed information what policies are being applied.

From what you’re saying I’m speculating that a policy is set within either:

Computer Config > Admin Templates > Network > DNS Client or

User Config > Admin Templates > Network > Network Connections

[zippo]

use the MMC resultant set of policy snapin on the station with the problem to determine the GPO's being applied.

The RSoP tool is invaluable in terms of sorting out what is actually happening at the station. You can see if there are any errors or conflicts, but most importantly you can see the winning GPO that is being applied and what values are being set.