disabling lame server logging

[Doug Barton]

You want to set up your resolver on your mail server to forward to your 
main resolver, using the forward only option. This will allow your mail 
server resolver to benefit from the cache already populated on your main 
resolver, while still maintaining the value of caching the answers 
itself locally.

Your goal of reducing the number of error messages in your main 
resolver's logs so that you can better chase down real problems is a 
good one. However you eventually reach a point of diminishing return 
where further reducing the errors ends up in you missing actual new 
problems.

Or, put another way, slogging through noisy logs is part of the job, 
given the horrific state of most DNS "out there." Welcome to the club.

Doug