[linux-elitists] DNS speedup

Jim Richardson warlock@eskimo.com
Thu Jan 15 13:31:46 PST 2004

On Thu, Jan 15, 2004 at 10:31:06PM +0200, Bulent Murtezaoglu wrote:
>>>>>> "JR" == Jim Richardson <warlock@eskimo.com> writes:
>    JR> Doing a simple nslookup, results in at least 1.5 seconds of
>    JR> delay, sometimes, as much as 4 seconds per, which would be ok
>    JR> on an initial lookup, but I get the same delay if I do the
>    JR> same lookup again, right after the first one returns. [...]
>Prolly isn't a BIND problem at all.  nslookup first looks up the
>details of the server it is using (forward if you give it a name,
>reverse id you give it an IP) and that might be where the delay is
>coing from.  Check what's in your resolv.conf for starters.  And then
>try testing with dig rather than nslookup.

I probably wasn't clear, sorry. The problem exists with nslookup, dig,
etc. I was testing from *another* machine, pointing to the suspect
machine's DNS server.  

I get the same slowdown on webpage serving, hit the url, then wait
2-4sec for the dns query to complete, then the pages are requested and
delivered fast. 

>    JR> ... 30 vhosts on this machine, it gets about 100,000 hits a day,
>    JR> (not counting ad impressions, which go to a different server)
>    JR> as you can guess, it's pretty busy and this isn't helping. Oh,
>    JR> if I drop the load, I don't see any improvement in DNS query
>    JR> times.
>That is not really high traffic for today's hardware.  Why is DNS
>relevant to you at all on this machine?  Are you doing reverse 
>lookups on each hit? 

Because the server hosts vhosts, and we want to control them within that
machine, rather than rely on the hosting provider to handle that. They
would charge a fee for each vhost, and profit margins are slim enough as
it is. :) 

Jim Richardson     http://www.eskimo.com/~warlock
Linux, The choice of a GNU generation.
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