Keep the Computer Browser Service Humming

In "The Computer Browser Service," June 2002, InstantDoc ID 24879, I explained that the Microsoft Computer Browser service maintains lists of your network's Windows-based domains, workgroups, and computers, as well as other network equipment that supports the NetBIOS protocol. These browse lists are the source of the information that users see when they expand Network Neighborhood in Windows Explorer. In Windows 2000—based networks, Active Directory (AD) replaces the Computer Browser service. However, mixed Win2K—Windows NT networks that maintain pre-Win2K domain controllers (DCs) and networks with some clients that aren't AD-enabled still use the Computer Browser service.

In the Computer Browser service, the domain master browser in an IP network interacts with network segment master browsers, relying on NetBIOS name resolution and several special NetBIOS names, to assemble lists of computers and other equipment. But what do you do when the Computer Browser service on your network breaks down? To prepare for this possibility, you need to know about the tools and procedures you can use to troubleshoot browser service problems.

A Healthy WINS
You'll find that NetBIOS name-resolution failures are a root cause of many incomplete browse lists. Make the effort to implement a robust name-resolution subsystem on your network, and many of your browsing problems will vanish. Microsoft recommends using WINS for NetBIOS name resolution. In a network with multiple broadcast domains (i.e., a network segmented by routers or Virtual LANs—VLANs), maintaining a system of WINS servers can be a lot easier than the alternative (i.e., maintaining client-based LMHOSTS files).

I suspect that most of you who've been responsible for WINS servers have had to deal with WINS database corruption—it seems to come with the territory. Compact and scavenge (remove obsolete information from) your WINS database regularly to avoid common WINS-related problems and browsing problems. For a list of articles that can help you maintain healthy WINS servers, see "Related Articles in Previous Issues," page 36. You can also find a detailed description of WINS at http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/windows2000serv/reskit/tcpip/part2/tcpch07.asp.

As you work through your browsing problems, you might come to suspect a NetBIOS name-resolution problem. To assist in determining a point of failure, see the sidebar "NetBIOS Name-Resolution Steps," which summarizes how Windows queries various sources during NetBIOS name resolution.

Browmon and Browstat
Microsoft provides two tools specifically for monitoring and troubleshooting the browser service: Browser Monitor (Browmon—browmon.exe) and Browser Status (Browstat—browstat.exe). When working with either tool, keep in mind that the computer you run them on limits them. In multiprotocol networks, both tools report browse lists only for the protocols that the local computer supports.

Browmon is a GUI-based utility in the Microsoft Windows NT Server 4.0 Resource Kit and the Microsoft Windows 2000 Resource Kit. For each domain you ask Browmon to monitor, it shows the status of the browsing subsystem for each protocol, as Figure 1 shows. Double-clicking a protocol returns the detailed information that Figure 2 shows, including the names of the master and backup browsers and the domains and servers on each browser's browse list.

Browmon reports only on the status of the local collision domain—that is, it sees only the local segment master browser and backup browsers. You can use Browmon to quickly see which computers are acting as master browsers and backup browsers for your domains and to compare these browsers' browse lists. Browmon automatically refreshes its display at a user-specified interval.

Browstat is a much more powerful tool. In addition to displaying browse lists and the names of browser computers, Browstat can force an election and reset the master browser. An older version of Browstat is in the NT 4.0 resource kit; an updated version is in the Windows 2000 Support Tools. Both versions have the same troubleshooting capabilities, but the Win2K version is easier to use. The earlier version requires that you include on every command the protocol name as the Net Config Rdr command displays it. For example, when I type the command

net config rdr

on my Win2K Professional workstation, it reports the TCP/IP protocol name as NetBT_Tcpip_{3F14F1D1-F77B-410E-8040-7582A8A889A2}. Thus, the earlier version of Browstat requires the following command on my system to display a list of backup browsers:

browstat gb NetBT_Tcpip_
  {3F14F1D1-F77B-410E-8040-
  7582A8A889A2}

(Gb, or Getblist, is the Browstat subcommand to retrieve a list of backup browsers.) Some protocol names on some systems are quite long, as you can see.

   Previous  [1]  2  3  4  Next