WINS-WINS Situation

In one domain where the servers seem to be missing, setting up WINS correctly may be the quick fix.

Bill: I'm an administrator in a small firm. We just opened up a branch office that connects to the main office via a VPN. I can ping all the servers in the home office from the desktops in the branch office using their IP addresses, so I know I have good network connections, but the servers don't appear in My Network Places and I can't ping them by name. Only the machines in the branch office show up in My Network Places. What's going on?
—Ralph

George: This is a classic Windows issue that fortunately has a simple fix. It involves a process called Browsing.

Every subnet has one Windows server (or a desktop with the Server service running) that takes on the role of Subnet Master Browser. The server assumes this role via an election process designed to select the most capable platform. If everything works correctly, servers win the election over gaggles of workstations and domain controllers win the election over member servers. The actual hierarchy is a little more convoluted than this, but you get the picture.

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The Subnet Master Browser keeps a little database of all the Windows servers on its subnet and their shared resources. It enlists the help of one or more Backup Browsers to host a copy of this database. When you open My Network Places, the desktop locates the Subnet Master Browser either using WINS or by broadcasting. The Subnet Master Browser refers the desktop to a Backup Browser, which delivers the contents of the database that you see in Explorer as a list of servers and their shared folders or shared printers.

Here's where things get interesting. Each Subnet Master Browser communicates its local browse database to a server called the Domain Master Browser. This is always the PDC of the domain, or the PDC Emulator in an Active Directory domain. The Domain Master Browser consolidates the various local subnet databases into a single master database which it then replicates to each of the Subnet Master Browsers. The Subnet Master Browsers replicate the consolidated database to the Backup Browsers.

Without a copy of the consolidated browse database, a Subnet Master Browser only knows of servers in its local subnet, which is the issue you're having in your branch office. To solve your problem, you need to figure out why the Subnet Master Browser isn't getting a copy of the consolidated database from the PDC Emulator.

The most common cause of the problem is improper WINS configuration. The Domain Master Browser registers a resource record in WINS. If a Subnet Master Browser needs to find this resource record before it can request a copy of the consolidated database.

In your setup, Ralph, you should have two WINS servers in the main office, one to act as primary WINS server and the other to act as a secondary for fault tolerance. Configure the two servers as push-pull replication partners. Point all Windows clients in both offices at the main WINS server for their primary server and the other WINS server as their secondary server.

If this does not solve the problem, identify the local Subnet Master Browser so you can figure out why it's misbehaving. Microsoft provides a tool in the Resource Kit called Browmon. The Browmon utility shows you the Domain Master Browser and Subnet Master Browser and Backup Browsers. Sometimes a Windows 9x box will insist on assuming the role of Subnet Master Browser even though a more capable machine should win the browse election. This can cause browsing problems. A Registry entry called MaintainServerList controls whether a machine will become a browser. Take a look at KnowledgeBase 136712 "Common Questions About Browsing with Windows" for details.

Hope this helps.

About the Author

Contributing Editor Bill Boswell, MCSE, is the principal of Bill Boswell Consulting, Inc. He's the author of Inside Windows Server 2003 and Learning Exchange Server 2003 both from Addison Wesley. Bill is also Redmond magazine's "Windows Insider" columnist and a speaker at MCP Magazine's TechMentor Conferences.

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