How to tell if passwords are NIS/YP/Hesiod served?

[Dave Sill]

I need to be able to tell, preferably portably, if the password file
on a system is served by NIS/YP.  Is the presence of a "+::0::::"
entry reliable?  I realize it could be there on non-NIS'd systems, but
that's OK.

I also understand Hesiod (e.g., Ultrix 4.0, or better) does password
service too.  Is there any reliable, portable way to tell if it's
runnning? 

Thanks in advance.

-- 
Dave Sill (de5 at ornl.gov)
Martin Marietta Energy Systems
Workstation Support