java.rmi.NotBoundException . Discovering what bindings are available

Below are the bindings of implementation of java.rmi.registry.Registry

CustomRegistry: registryCount = 2
reg1.com:11, # of bindings = 2
 OPTIONS
 UPDATES
reg2.com:11, # of bindings = 1
 TEST

When I use

(MyRegistry)registry.lookup("OPTIONS");

I receive exception: java.rmi.NotBoundException: OPTIONS

After reading explanations of this exception on this site then it appears the binding "OPTIONS" is not discoverable.

As the RMI servers are on a different machine is there a mechanism I can use to discover the bindings available on servers reg1.com % reg2.com