[rbldnsd] TTLs and negative caching

[Jeff Chan]

We run SURBL which has RBLs containing spam URI domains.
They are used to block spam based on URI domains contained
in message bodies.

Currently some of our zone files have fairly long TTLs
of several hours.  This appears to be causing new entries
to take several hours to become active.

1.  Does that sound right?  In other words does TTL apply
to negative caching or only to positive caching (or to both).
By observing the behavior of an rbldnsd installation, TTL
does seem to affect negative caching.

2.  Can we expect a lot more DNS traffic if we lower our
TTLs to say 10 minutes?

Thanks in advance for any advice,

Jeff C.
-- 
Jeff Chan
mailto:jeffc at surbl.org
http://www.surbl.org/