A: When you enable vSphere 5.0's vSphere HA, the vCenter server provisions Fault Domain Manager (FDM) agents to each host in the cluster. The list of cluster hosts is also pushed to each FDM agent in parallel, enabling FDM agents to asynchronously engage in a master election. During this period, vCenter probes agents for the master, sending an alert if the election takes too long.
This parallel provisioning approach is different from the previous version's serial approach. It's expected to reduce cluster configuration time to less than one minute rather than the previous version's one minute per host.