Grid Control agent monitor multiple IPs on single server

If you have one server that has multiple databases with multiple listeners that have DIFFERENT IP addresses but co-exist on the same server, do you have to have separate Grid Control agents to monitor the different ip addresses or would you still have just one agent for the server itself and it could still discover everything?  

For example, if you wanted to be able to monitor whether each individual listener is up, could one agent do that even though the IPs are different? This is a 10.2.0.5 agent on Linux running Standard Edition with 11.1.0.7 databases.                                                 

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