I have a domain of 50 or so workstations. All have SUNWcstu version 3.5
installed on them. NIS is set up for a minimal amount of local mounts and
quite a few mounts on NIS in auto.opt.
There is a problem with the startup script /etc/rc2.d/S95cst.
The author of the script put in these two lines:
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/SUNWsrs/lib
export LD_LIBRARY_PATH

The SUNWsrs package isn't installed on the workstations.
CST likes to monitor these workstations, and causes several
NIS queries every 30 seconds to 1 minute because automount
forces a search for the SUNWsrs mount.
Several queries multiplied by 50 or so workstations adds up,
and running one of the NIS masters on an old Ultra-1 doesn't help.

The workaround is commenting out the above two lines, then stopping
and starting cst, on every workstation.