Are you sure about this ? Even with maps located on a network mapped drive ?
If you mean "transferred by the DR system" here (as I assumed):
Are all the maps in the current scene transfered to the render nodes ?
then yes. As said, the assets have to be accessible by the node as if it would be required when opening and rendering the scene on that slave in Max "manually". In case of using mapped drives, the user running DrServer.exe would only need to have that drive mapped as well (does not work when running DrServer as windows service, you have to use unc names in that case). Then, if an asset is not reachable/missing, the dr system forwards the missing asset to the slave(s).
You can easily check what happens in your environment by going to
%userprofile%\appdata\local\Coronarenderer\Drdata
of the user running the DrServer and checking what has been sent by the master. The transferred files should also be listed in detail in the file "drlog.txt" inside of that directory.
What you see in task manager are most probably just the slaves loading their assets across the network, using the standard scene paths. Slaves have to load the scene assets sooner or later of course, either directly through valid network paths/valid local paths or with the help of the master from the Drdata directory.
Good Luck