Netware 5.1 SP7

How do I set the DNS to clean out old items?

I have searched the KB on Novell, I poked around the Management Console, but
am having no luck. It doesn't seem to delete any old items from my domain
unless I do if manually.

My values for the
Refresh: 180 Min
Retry: 60 Min
Expire: 168 hours (7 days)
Min TTL: 24 hours