"reasonable" bulk resolver behavior

Steve Friedl steve at unixwiz.net
Thu Jan 13 00:15:44 UTC 2005

Hello all,

I've written a bulk IP rDNS resolver program that runs through Apache
logs and populates a DB file with IP->name lookups that are later used
by webalizer for webserver logfile analysis. It uses the ADNS library to
make async calls (in a single thread) to burn through reverse lookups as
fast as the network can take it: there could be 200 outstanding queries
at a time, for instance.

It strikes me that maxing out the nameserver is not terribly polite
behavior, so there is a throttle mechanism: limit to <N> outstanding
queries at a time, and pause a bit when we reach that number.

How does one select a proper throttle point for a nameserver? I have
no idea when the query rate becomes "rude": can anybody offer some
suggestions for what to look for when picking this number?

Thanks all.


Stephen J Friedl | Security Consultant |  UNIX Wizard  |   +1 714 544-6561
www.unixwiz.net  | Tustin, Calif. USA  | Microsoft MVP | steve at unixwiz.net

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