.. _teamdrive name server (tdns)/connecting users between different registration servers:

Connecting users between different Registration Servers
-------------------------------------------------------

The TeamDrive Name Server (TDNS) settings are one of the more important
settings which must be defined
during the setup and which can not be enabled later on when users are already
registered on your Registration Server.

The TDNS helps send invitations between users which are registered on
different Registration Server by mappings the user to their respective servers.
This is necessary because invitations must be send to the Registration Server
for which the user is registered with their devices.

Usernames, unlike email addresses, are unique within the TDNS network.
If you enable TDNS access, any username that is already in use by a server
within the TDNS network can not be used by your own Registration Server.

TDNS access will modify the registration, login, search and invitation calls
in the Registration Server (as well as the API calls) and check the TDNS, 
determining which username exists on which Registration Server in
the TDNS network.

Every Provider requires a record on the TDNS. A record will have a *ServerID*
and a *checksum*. All requests will contain the *ServerID* and *checksum* to
verify that the request is coming from a valid Registration Server.

You have to enable outgoing access on the HTTP-Port 80 to ``tdns.teamdrive.net``
to enable the communication from your Registration Server to the global TDNS.