For production installations, you rely on redundant systems, load balancing, failover capabilities, and server replica to provide high availability. You therefore typically create servers on multiple host systems. Yet, more powerful host systems might each house multiple server instances.
When you create multiple server instances on a single host system, only one server instance can listen on the default ports. As long as you install Directory Server Enterprise Edition software only once, multiple server instances can share the same common agent container.
When you install multiple Directory Server Enterprise Edition versions on a system, each version comes with its own common agent container. Only one of those common agent containers can listen on the default port for JMX management traffic.