Wednesday, July 14, 2010

Windows 2008 and NETBIOS browsing


It has been reported that NETBIOS is on its way out; however as most have found out, it is still a critical part of most Windows Environments.  This article will explain issues that may surface during the implementation/upgrade/migration to Windows 2008 server environments.

When installing a new Windows 2008 server or upgrading an existing server to Windows 2008, the Computer Browser service is set to disabled by default.


If you upgrade the Domain Controller that has been assigned the PDC Emulator FSMO role over transfer that role to a Windows 2008 DC, you will see the domain wide NETBIOS network browse list shrink and remote subnet machines will disappear from the list.  Eventually you may only see computers from the local subnet in the network browse list.  If you have subnets with only one server and it is Windows 2008, then you may also see inconsistent local subnet browse lists due to clients taking a master browser role and they may be rebooted, turned off, etc.


To resolve this problem, you can either set the Computer Browser service to Automatic on the DC holding the PDC role, or move the PDC role to another DC that has the Computer Browser service started.  You will need File and Printer sharing On in the Network and Sharing Center, otherwise the Computer Browser service will fail to start since the required ports will not be open.  In a multiple subnet environment, make sure WINS is configured properly so that you have the proper NetBIOS name resolution.  After making the corrections, the computers holding the master browser roles will begin to populate the browse list for the entire network.

Additional Checks;

Registry and TCP/IP configurations on the DCs for Browser parameters.

  • TCP/IP Configuration:   Verify NetBIOS over TCP/IP is ENABLED
  • Registry parameters: 
    • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Browser\Parameters\IsDomainMaster = TRUE
    • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Browser\Parameters\MaintainServerList = AUTO

Note:  You should reboot the PDC after making the change.


Tools to help troubleshoot the NETBIOS Browsing Issues:

  • BROWSTAT.exe (Resource Kit)
  • NBTSTAT (Native to the Windows system)


Command Usage Checks Steps
net view view the browse list available to the client machines and the servers hosting WINS If a list of machines are presented, validate the which subnet the machines are located using “Ping”.  Does the subnet match that of the machine running the command?  Document a machines from different subnets to see what is displayed for each.  This will help in the troubleshooting process.

Some steps I use from a test machine:

  1. IPConfig /all
    • Verify WINS Servers
  2. IPConfig /FlushDNS
    • Flush DNS resolver cache
  3. NBTSTAT –n
    • Check Local Names table
    • Release and Refresh Registration
  5. net view
    • Check browser list

Local Name Table check status column for “Conflicts”.  If conflicts exist, you may have to clean up WINS.  Either remove the problem records or rebuild WINS DB (Easier to rebuild).

Note:  If status column lists Registered or Registering you can release and refresh the registration.  NBTSTAT –RR

Then check the NBTSTAT –n results.
Rebuild WINS DB>
1.  Stop WINS Service
2. Backup WINS DB to alternate location.
3.  Delete WINS directory contents
4.  Start WINS service, and the db will rebuild.
5.  Create necessary replication partners, but DONT pull from other possibly infected WINS DBs, unless they are cleaned prior.
browstat dn To get the transports bound to the interface(s) Use the correct interface number (ex. 1) for the next command.  Browstat getpdc 1 <Netbios domainName>  
browstat GETPDC 1 contoso Get the machine with PDC role Run this check from machines that cannot see the browser list properly, as well as the WINS servers themselves.  
browstat GETMASTER 1 contoso Get the master browser    


1 comment:

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