The binding process in server-list mode works as follows:
ypbind looks in the /var/yp/binding/domainname/ypservers file for a list of NIS servers for the domain.
ypbind initiates binding to the first server in the list. If the server does not respond, ypbind tries the second, and so on, until it finds a server or exhausts the list.
ypbind tells the client process which server to talk to. The client then sends the request directly to the server.
ypserv sends the requested information back to the client.