Blog: DFS

I have a few notes to share on DFS in Windows 2008 R2. First of all, Microsoft changed the way DFS replication is done starting in Windows 2003 R2. In previous versions, DFS replication for SYSVOL shares on domain controllers as well as DFS replications was handled by FRS (File Replication Service). Starting in Windows 2003 R2, the service was overhauled along with the management interface. Replication for DFS is now handled by DFS Replication Service and the two (DFSR and FRS) don’t play ball with one another. That is to say that you can’t use pre-windows 2003 R2 servers in the same DFS replication topologies with post-windows 2003 R2 servers. However, SYSVOL in all versions continues to use FRS until all domain controllers are Windows 2008. Additionally, once you have your DFS tree in place and get your replication topology set up, you’re not done. Make sure to edit the file exclusions list for the replication group. By default, a new replication group EXCLUDES files with the ~ (to start the file), .tmp, and .bak files. The ~ makes sense, but .tmp and .bak could be  a problem depending on the type of data in the share.


I had an issue with an XP workstation this week where a user could not connect to a certain dfs link in the dfs tree. The tree contained three root shares, one of those being the Apps folder. None of the PCs could map a network drive to the \\domain\Apps folder from explorer or using NET USE command. However, if the direct referral location was used (\\server\data\apps$), everything worked, so it wasn’t a permissions issue. After much troubleshooting and a couple reboots later, I came across an article regarding this issue ( The issue is with XP SP3, of which each computer that was having issues had installed. The issue results from a corrupted DFS link entry in AD. XP prior to SP3 would ignore it, but SP3 will not. The solution is to delete and recreate the DFS link and then purge the DFS mup cache on the client by using the following commands (dfsutil is part of windows 2k3 support tools) [more]

Dfsutil /pktflush

Dfsutil /PurgeMupCache