Source is available as a compressed tar file. This is inefficient, and can be quite slow if the group map is large. In addition, the group map is not cached locally, so the request must always go to the NIS server. When many workstations and servers all run the same cron commands at exactly the same times, the simultaneous requests can overload the server, causing it to run out of file descriptors or connections. This can most simply be done at boot time with init.d scripts.
Source is available as a compressed tar file.