DFS is a feature that allows foreign UNC paths to be presented as one unified tree. This is helpful because you don't need to tell your users to connect to several servers and have them remember the server names.
For example, say your QNAP is at \\my-nas, and you have a second Windows server with a share \\my-server\PublicFolder.
You can create a DFS link called \\my-nas\LinkA which actually connects you to \\my-server\PublicFolder.
The normal username/password rules apply, you are not squashed into a user when you connect through \\my-nas\LinkA\, you must actually have a valid account on \\my-server
The downside is that if your DFS aggregator (the QNAP in this case) goes down, users lose access to this redirection portal, you will have to tell them to connect to the actual server directly.
Does the NAS support DFS?
Yes, QNAP firmware supports DFS in the form of a feature called "Folder Aggregation" and "Portal Folders". Keep in mind however, that the official DFS implementation from Microsoft supports both redirecting UNC paths **and** replication of those folders locally to provide higher performance to local users and replication over WAN links using a bandwidth efficient method.
The QNAP implementation, being based on Samba, doesn't bundle replication in with DFS. If a remote server goes down as in the example above, \\my-nas\LinkA will fail to work.
OLD Does the NAS support DFS?
Yes, it does, but only by manual editing of the smb.conf .
To activate DFS add a line in this global section:
[global] host msdfs = yes
and activate a share like this in your shares definitions:
[dfs] comment = DFS path = /share/HDA_DATA/DFS msdfs root = yes
To create now a dfs link with
ln -s msdfs:\\myserver\\datashare /share/HDA_DATA/DFS/mydata