tools to manage the cache of bind?

[Jonathan Tse]

I am working in an isp and take care of the dns. It looks quite simple. But
everyday I got a number of complains that our dns caches the not-up-to-date
data. Sometimes the complains are from the customer and ask me to restart
the named. But our side is unwilling to do so as dns is the most critical
thing to us. So is there any tool for me to just take out a record or a zone
from the cache in order to speed up the refresh of that particular zone?

Best regards,
Jonathan.