In the first SYNOPSIS line, the nisping command sends a ``ping'' to all replicas of a NIS+ directory. Once a replica receives a ping, it will check with the master server for the directory to get updates. Prior to pinging the replicas, this command attempts
to determine the last update "seen" by a replica and the last update logged by the master. If these two timestamps are the same, the ping is not sent. The -f (force) option will override this feature.
Under normal circumstances, NIS+ replica servers get the new information from the master NIS+ server within a short time. Therefore, there should not be any need to use nisping.
In the second SYNOPSIS line, the nisping -C command sends a checkpoint request to the servers. If no directory is specified, the home domain, as returned by nisdefaults(1), is checkpointed. If all directories, served by a given server, have to be checkpointed, then use the -a option.
On receiving a checkpoint request, the servers would commit all the updates for the given directory from the table log files to the database files. This command, if sent to the master server, will also send updates to the replicas if they are out of date. This option
is needed because the database log files for NIS+ are not automatically checkpointed. nisping should be used at frequent intervals (such as once a day) to checkpoint the NIS+ database log files. This command can be added to the crontab(1) file. If the database log files are not checkpointed, their sizes will continue to grow.
If the server specified by the -H option does not serve the directory, then no ping is sent.
Per-server and per-directory access restrictions may apply; see nisopaccess(1). nisping uses NIS_CPTIME and NIS_PING (resync (ping) of replicas), or NIS_CHECKPOINT (for checkpoint). Since the NIS_PING operation does not return a status, the nisping command is typically unable to indicate success or failure for resyncs.