Thanks for the explanation - it's easy to understand. I have some questions though: 1. Take a scenario where there are 4 nodes A,B,C,D but only 2 nodes have come up so far. What happens to HASingletonController_3 if only first 2 nodes are running. If I understand correctly it will do a mod of (3 % 2). Which means that HASingletonController_3 will be started on node B. Now what happens if Node 3 comes up and eventually Node 4. Would the master change everytime a Node joins a cluster? 2. In scenario where all nodes are running, is it correct to say that HASingletonController will be in "start" state in only one of the nodes and all other nodes it will be either created/stopped. 3. Why does HASingletonController depends on HASingletonMBeanExample_1, shouldn't it be other way round? I thought HASingletonController is responsible for starting/stopping the MBean. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4188274#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...