DFS in Windows Server 2003 R2 is supposedly limited to around 5000 DFS links per domain-based root. But actually the limitation is not in the number of links but in the size of the blob used for storing DFS link information. This blob (bimary large object) size limitation is 5 MB for domain-based DFS roots, but how do you know when you are approaching that limit? Here's how:

1. Start the DFS Namespaces console.
2. Right-click on the domain root and select Properties.
3. Under the Namespace Size heading, look at Size In Active Directory. If this is approaching 5 MB then you're running out of room and shouldn't try to add any more links.

For more information about new DFS features in R2, see my articles titled Implementing DFS Namespaces and Configuring DFS Namespaces here on WindowsNetworking.com.