Hey Jonu,
correct, the list there is a bit misleading.
What it seems to display is the list of hosts that either are MASTER or SLAVE coordinators in distributed systems. (check against M_SERVICES.COORDINATOR_TYPE).
In the HANA Studio you can check the "Index Server Role (actual)" for this.
In addition to this, the list will contain any host you explicitly entered into the connection detail when you defined the connection.
Anyhow, the complete list of all hosts and there roles is also stored in the system landscape file:
.. \hdbstudio\.metadata\.plugins\com.sap.ndb.studio.datamodel\hdbstudio.xml
In case the MASTER host is not reachable, the STANDBY node is tried to get connection information.If this one is either not reachable either or reports to be not the MASTER yet (because no take over occurred) the connection will fail.
Once one of the coordinators is actually reached, the current landscape information will be delivered to the client again and the SQL connection can be established with one of the available SQL services.
Hope that makes it a bit easier to understand.
- Lars