The DFS MP is a converted MOM 2005 MP and as can be seen by its version number(6.0.5000.0) it is quite old. It has not been updated since being converted. There was an update but that was only to the document. The October 2008 updated release of this management pack includes the following change:
References to support of Microsoft Windows 2000 Server have been removed from the guide included in the download.
The DFS Management Pack monitors the Distributed File Systems service on computers that are running Windows Server 2003. The DFS Management Pack does not monitor computers that are running Windows 2000.
I installed this at a customer site as they had DFS and wanted to monitor their DFS shares. This created almost 600 alerts. A bit overwhelming. This is a case where a test server would have been useful.
On one of the KB Research post it said that this problem could be caused by having the wrong version of the Windows Support Tools installed. The MP uses dfsutil.exe to do the monitoring and so needs the Windows Support Tools installed. The customer did indeed have older versions of the tools with SP2 servers but having updated the tools it did not help but was done as a matter of course as they should be in synch.
The DFS Management Pack rules must be configured with the installation folder of the Dfsutil.exe utility. It is recommended that you install the utility in the same folder on all your computers. This was checked and it was in the same directory and the default as used by the MP so that was fine.
As some (very few) DFS links showed up green this was investigated and it looked like a rights issue, After testing this was confirmed. As the MP is old it does not have a Run As account so the customer is having to go through all the DFS shares to ensure that the agent local system account can access the shares so that they can be monitored correctly. It would be nice to get an update for this MP.
As well as the MP guide there are 2 good posts from J.C. Hornbeck
No Health State for DFS Link Targets
DFS Management Pack Generates Bogus DFS Link Monitor Alerts
Which describes the problem.
This can occur when the DFS servers use Local System for the Default Action Account. Computer accounts do not have permission for file shares unless the share and NTFS security ACLs include the Authenticated Users principal. Therefore, if the DFS Link Monitor runs using Local System credentials, the monitor will detect the shares as being unavailable. The solution offered here is to create run as account and assign to all DFS servers. It does mean that all the rules except ones assigned to various run as accounts will run with this new run as account. This is something that the customer did not want to do but is an option.
It can get very confusing with FRS, DFS, DFS Replication and DFS Namespaces as it depends on which version of the server OS you are using.
Overview of DFS
DFS Technology Center