Host command timing out sporadically

[Paul Marais]

Hi,
I'm having an issue where my postfix server is having trouble with some lookups.
When I type 'host <hostname>', 80% of the time I get decent reply speed, but for 20% I get a 5 second delay, or even a timeout.

My nameserver is configured to only allow recursion for hosts on my local network, and I have my ISP dns in my forwarders.
My resolv.conf has 127.0.0.1, my internal ip, and the ip for my isp DNS

Any help will be greatly appreciated.

Thanks
Paul