The hosts to which the ISession is connected to, at the time this state was obtained.

Please note that this method really returns the hosts for which the session currently holds a connection pool. As such, it's unlikely but not impossible for a host to be listed in the output of this method but to have GetOpenConnections(Host) return 0, if the pool itself is created but no connections have been successfully opened yet.

The number of queries that are currently being executed through a given host.

This corresponds to the number of queries that have been sent (by the session this is a State of) to the server Host on one of its connections but haven't yet returned. In that sense this provides a sort of measure of how busy the connections to that node are (at the time the state was obtained at least).

The number of open connections to a given host.