An important feature of the NG/AMS Server is the ability to execute in a cluster environment.
	The same SW is used both for the online archiving and for the archive cluster facility. If a private network is used within the cluster, it is possible to define one of the nodes as master. This will then be the main contact point for external clients when e.g. retrieving data. The proxy server will retrieve the file from its actual location and return it to the  requestor. In principle the file can be stored on any NGAS Node accessible via HTTP. I.e., also files stored on nodes at the observatory sites can be retrieved by a proxy server.
	In the example above, the file is stored on a sub-node in a sub-cluster within the  NGAS Cluster. The contacted node identifies the best suitable file for the request. In this case it identifies that the file is stored in another private network and contacts the Main Node of the sub-cluster. The sub-cluster main node locates the file and requests this from the sub-node. The file is subsequently send back to the contacted main node and streamed through to the requestor.
	The best suitable file is determined according to the following criteria:
	1. Local host location.
	2. Location within same cluster.
	3. Location in the same domain.
	4. Any IP address.
	Before deciding which file to choose for a query, it is checked if the file is actually accessible.