Browsing Across Subnets w/ a Multihomed PDC in Windows NT 4.0

ID: Q158487

The information in this article applies to:

Microsoft Windows NT Server version 4.0

SUMMARY

In Windows NT versions prior to 4.0, it was not possible to browse across subnets that were connected by a Windows NT Primary Domain Controller (PDC) server configured with TCP/IP routing and the Windows Internet Name Service (WINS).

This article explains how to configure this functionality with Windows NT 4.0.

MORE INFORMATION

Windows NT 4.0 provides a new registry parameter that allows the computer browser service to be disabled on one or more network interfaces. When this registry parameter is added, it enables a multihomed domain master browser to provide a comprehensive browse list to computers on all subnets.

NOTE: When enabling this parameter, the assumption is made that all other TCP/IP connectivity (ping, net use, and so forth) are functioning correctly. This parameter only changes browser functionality, and will not fix client problems, such as incorrect default gateway, or server problems, such as incorrect IP addressing or routing problems.

Steps to enable this feature:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

Run Registry Editor (Regedt32.exe).

From the HKEY_LOCAL_MACHINE subtree, go to the following subkey:

SYSTEM\CurrentControlSet\Services\Browser\Parameters\

From the Edit menu, select Add Value and use the following entry:
```
      Value Name: UnboundBindings
      Data Type:  REG_MULTI_SZ
      String:     NetBT_<name of network adapter driver to be disabled> 
```
If you have more than 2 network adapters in the multihomed Windows NT server, enter each driver instance you wish to disable on a separate line in the String field.

For example, if you need to disable the browser binding for an Intel EtherExpress Pro network adapter, the string would be NetBT_EPRO1. To determine the name of your driver for your network adapter, look in the
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services key for a name that corresponds with your network card.

NOTE: There will be at least two entries for each network adapter--use the one that ends with a number. For example, when the Intel EtherExpress Pro network adapter driver is installed, it adds EPRO and EPRO1 entries in the Services registry key. The EPRO entry corresponds with the binding and driver information for all EtherExpress Pro cards that are in the computer, and the EPRO1 entry is for one specific instance of the driver, with specific settings for one particular card. If a second EtherExpress Pro card were added to the computer, an EPRO2 entry would be added to the registry and would contain card-specific information (IRQ, I/O address, and so on).

Quit Registry Editor.

Shut down and restart Windows NT.

Once Windows NT restarts, you can test if the UnboundBindings parameter worked by inspecting the Event log. There should be only one browser 8015 event ("The browser has forced an election on network \Device\NetBT_NETFLX2 because a Windows NT Server (or domain master) browser is started.") that corresponds with the card for which you have not disabled the browser binding.

NOTE: As in previous versions of Windows NT, if WINS is configured incorrectly, browsing (and name resolution) will not work as expected. On a multihomed PDC running WINS, as described earlier, all WINS entries (primary and secondary) on all adapters should have the IP address of the one network adapter that has the browser service enabled. The following information is an example of the output of the IPCONFIG /ALL utility:


Windows NT IP Configuration

   Host Name . . . . . . . . . : nctag
   DNS Servers . . . . . . . . :
   Node Type . . . . . . . . . : Hybrid
   NetBIOS Scope ID. . . . . . :
   IP Routing Enabled. . . . . : Yes
   WINS Proxy Enabled. . . . . : No
   NetBIOS Resolution Uses DNS : No

Ethernet adapter EE161:
   Description . . . . . . . . : Intel EtherExpress 16 Miniport
   Physical Address. . . . . . : 00-AA-00-47-54-26
   DHCP Enabled. . . . . . . . : No
   IP Address. . . . . . . . . : 200.200.201.1
   Subnet Mask . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . :
   Primary WINS Server . . . . : 200.200.201.1
   Secondary WINS Server . . . : 200.200.201.1

Token Ring adapter NETFLX2:
   Description . . . . . . . . : Compaq NetFlex Driver, Version 1.10
   Physical Address. . . . . . : 00-01-FA-12-D7-A2
   DHCP Enabled. . . . . . . . : No
   IP Address. . . . . . . . . : 200.200.200.1
   Subnet Mask . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . :
   Primary WINS Server . . . . : 200.200.201.1
   Secondary WINS Server . . . : 200.200.201.1

In this example, the UnboundBindings value is set to NetBT_NETFLX2, and clients on the 200.200.200.0 and 200.200.201.0 subnets can browse and connect to each other.

For additional information, please see the following article in the Microsoft Knowledge Base:

ARTICLE-ID: Q133241
TITLE : Browsing Domain Master Browsers w/ Multiple NICs and Protocols

Additional query words: prodnt

Keywords : kbnetwork kbbug4.00 nttcp NTSrv
Version : 4.0
Platform : winnt
Issue type :