Important programs associated with NIS

• ypserv daemon
  • A single daemon, ypserv handles all client requests.
  • Three sets of procedures: client lookups, map maintenance calls, and NIS internal calls.
  • Request is answered if the domain has a sub-directory in the NIS server directory. That is, a request for service to domain "impact" will be answered if the /var/yp/impact directory exists.

• ypbind daemon
  • Runs on the client machines.
  • Binds on startup to default domain.
  • Broadcasts a request for service
  • ypbind keeps track of the server to which it is currently redirecting requests
  • Until it is explicitly told by the NIS RPC timeout that the server is not responding in time.

• portmap
  • The RPC portmapper is a server that converts RPC program numbers into TCP/IP (or UDP/IP) protocol port numbers.
  • Must be running in order to make RPC calls which is what the NIS client software does to the NIS server.
  • When a client wishes to make an RPC call to a given program number, it will first contact portmap on the server machine to determine the port number where RPC packets should be sent.