Re: djbdns: Current recommended patches?

On Tue, May 19, 2009 at 8:16 PM, David Nicol <[email protected]> wrote:
> how often does a  second query arrive for the same cacheable name
> before a cached answer is available from the first query, in real
> world conditions, outside of an attack?

I've witnessed on our office network queries for names within our
network being asked multiple times.  E.g., if we've recently flushed
our DNS caches and then restart some of our services, at startup time
they all send the same queries, which may not yet be cached.

It also happens a lot for names that take a long time to resolve.
E.g., tools.ietf.org and levkowetz.com used to use name servers within
each other's domain, which caused dnscache to go crazy trying to
resolve www.tools.ietf.org.  Clients would time out waiting for the
cache to respond and repeat the query, so dnscache would have multiple
query resolutions for www.tools.ietf.org running at once.

Why do you ask?