I think it’s controlled by the contents of nsd.ini. I’ve got it enabled on my client and below is a dump of the contents. If you have access to a client where it isnt’ enabled, you can compare the differences. I’d be curious to know if this helps.
Point 1: Whether you run the client or the server, and whether or not you have Fault Recovery enabled on the server, all of the system resources used by the client/server are removed/cleaned up. This means that you can start either the client or the server immediately after a crash and NSD has run. This is still true even if you are running 6.5 and disable NSD on the server. From Release 6.0 forward, in no case do you have to do anything extra after a crash in order to be able to restart the client or server1.
Point 2: After the above has completed, if Fault Recovery is enabled then the server restarts automatically. This is a good thing because servers often run unattended and can experience problems when nobody is available to restart them. Clients, on the other hand, are always interactive and therefore can always be restarted manually. An automatic restart of the client is unnecessary … it’s just a mouse click away.
(1. There are cases where a backup program, antivirus software, or other program is running which prevents the complete cleanup of system resources. We are continuing to work on those issues.)