First of all, I want to make it clear that I don't have the answer to your question.
As you are still in testing phase, may I ask you why did you choise NIS Server instead of LDAP?
Don't take it wrong, there is no offence here, but I would personnaly have chosen LDAP to setup a centralise authentication system.
You will find much more documentation on how to setup an LDAP server and all the authentication system which goes arround, than with a NIS server (which I would personnaly consider as deprecated or obselete)
On top of that, if you consider how many applications are supporting LDAP authentication nativly Vs NIS server, this is not a negligable argument as well.
The directory Fedora project can help you to setup an Open-LDAP server quite easily.
I hope that will help,