I get very strange errors with /etc/exports. If I have something like this
in /etc/exports:

/usr/local		foo.example.com(ro)
/export/redhat-6.2	newbie.example.com(ro)

After restarting nfs, showmount might tell me something like this:

/usr/local		foo.example.com,newbie.example.com
/export/redhat-6.2	(everyone)

I've even managed to make it export /usr/local to the world, writable, even
when all options in /etc/exports are explicitly read-only. This sucks.

I can manually edit /var/lib/nfs/etab and /var/lib/nfs/xtab to make it work
as I want; this seems to indicate that the problem is with the exportfs
utility. This is a pretty serious problem though.