If you’ve used the Distributed File System snap-in in Windows Server 2003, you might’ve seen the checkbox called “Publish this root in Active Directory.” You might’ve even checked it and wondered what benefits it provides. Does it somehow make a namespace more fault-tolerant? Does this make the namespace part of Active Directory? Just what does it do?? And if you’re an eagle-eyed fan of DFS, you might have noticed that (A) nothing seems to happen when it’s checked or unchecked and (B) the checkbox doesn’t exist in the new DFS Management snap-in in Windows Server 2003 R2.
So here’s the scoop: The checkbox is broken in Windows Server 2003. I think the original intent was to make the namespace appear in Active Directory searches. But even if the checkbox worked, this wouldn’t affect the functionality or fault tolerance of the namespace in any way whatsoever. What makes a namespace fault tolerant is where and how the root is hosted. For a stand-alone namespace to be fault tolerant, the root must be created on a server cluster. For a domain-based namespace to be fault tolerant, you need at least two domain controllers in the domain (to provide referrals to the namespace) and two namespace servers hosting the root (to provide referrals to folder targets). This last point about domain-based namespaces is often misunderstood, too. Customers think that because the namespace is in Active Directory, this somehow makes the namespace fault tolerant. The AD aspect is more about consistency than redundancy. All namespace servers will poll a domain controller periodically to obtain the latest DFS metadata, helping ensure that all the namespace servers provide referrals that are consistent. You still need an operational domain controller and namespace server (which can be the same server) to provide referrals.
Want to know more about how a namespace works? Check out the DFS Technical Reference.