Do not reboot! Do not issue any more nisping commands.
When performing a nisping or checkpoint, the server will be sluggish or may not immediately respond to other commands. Depending on the size of your namespace, these commands may take a noticeable amount of time to complete. Delays caused by checkpoint or ping commands are multiplied if you, or someone else, enter several such commands at one time. Do not reboot. This kind of problem will solve itself. Just wait until the server finishes performing the nisping or checkpoint command.
During a full master-replica resync, the involved replica server will be taken out of service until the resync is complete. Do not reboot--just wait.