It depends of what you want to do :
to get the list of the monitored hosts, do a search on the host
get the list of your existing forwarders, enable the "Deployment Monitor" app and look at the reports of the forwarders
to add new indexers, and load balance your data between all your indexers :
Here is the classic procedure to add a new indexer to the cluster.
On the new indexer,
define all the indexes,
setup all the props/transforms required for the indexing of your sourcetypes.
open the listening ports (splunktcp 9997 by example)
List item
On the search-head,
add the new indexer as a search-peer (manager > distributed search)
On each forwarders :
edit outputs.conf to add the new indexer to the tcpout server list
for details http://docs.splunk.com/Documentation/Splunk/4.0/Admin/Configureround-robindatabalancing
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