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I have a BIND nameserver on my network sitting on a machine with a lot of RAM. How can I increase performance? Any way to increase the TTL for which resolutions are stored in memory? Any way to "pre fetch" top domain names?

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up vote 5 down vote accepted

BIND does it's own memory management, and so long as you've got plenty of RAM free no tweaking is necessary. Please do not screw with TTLs or anything else specified in an RFC. Seriously, people will want to hurt you just for asking that question. As for pre-caching, you can certainly do a nslookup for all the various "common" domain names you want cached, but there should be relatively little benefit to this.

It sounds like you're either chasing performance without a performance problem, or not filling us in on the actual problem you're facing. If it ain't broke, don't fix it. If DNS lookups are taking a notable amount of time you may want to use your ISPs (or other relatively-local) DNS servers as forwarders, as their "distance" should be less than your server doing fully recursive lookups, and you'd get the benefit of their caching as well.

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Thanks for your thoughtful answer. When I run Google's "namebench" DNS benchmarking tool, my local DNS servers are always slower (3-4x) than OpenDNS or Google's servers. Even when I forward my queries to one of these servers, it's never as fast. – ensnare Aug 24 '12 at 15:58
First, NameBench doesn't belong to Google, it's just hosted on their site. Second, you're probably looking at the average time, which is a terrible measure; and the program further corrupts that measure by including the time spent waiting for Timeouts in the average. I just tested my servers, it shows "OpenDNS is 490% faster" than my primary server. But the graph shows a different story with 90% of queries coming in from my server much faster than OpenDNS. The last 10% drag the "average" up that much. Also my server's fastest time was 33x faster than OpenDNS. – Chris S Aug 24 '12 at 16:17

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