To back up an entire NIS+ namespace you run the nisbackup command on the root master server with the -a option.
When you use the -a option, you do not specify the NIS+ directory objects to be backed up. All NIS+ directory objects on the server and all those of subdomains below it will be automatically backed up.
For example, to backup the doc.com. namespace to a /master1_bakup directory, you would run nisbackup on the root master as follows:
rootmaster# nisbackup -a /var/master1_bakup