Bind 9.1.3 stop resolving but is still running.

[Brad Knowles]

At 11:24 AM -0700 9/5/01, Nate Campi wrote:

>  What happens to me is that I'm running an app that does resolution on
>  IPs for our reporting team, as fast as BIND can handle it. BIND 8
>  handles up to around 800 queries per second, but BIND 9 handles at most
>  half of that, and stops resolving for 45 seconds to a minute at a time.
>  This happens every two or three minutes. Running BIND 9 at debug level 3
>  shows it answer a lot of queries, then stop answering the client
>  resolver while doing a bunch of "createfetch" operations. BIND 9 never
>  stops responding to kill or HUP signals, but pauses on answering new
>  queries.

	Have you tried other tools?  The netperf3 package is used by Rick 
Jones to do benchmarking of BIND 8 & 9, and he has demonstrated on 
his systems that both can do up to at least 12,000 DNS queries per 
second.  There are some benchmarking tools that come with the latest 
betas for BIND 9.2.0, and I believe that you could use them to 
demonstrate what kind of query rate your systems should be able to 
handle.

>  It is as if BIND 9 is having trouble with unresponsive name servers, and
>  not answering additional queries while it tries to resolve the current
>  IPs. This is of course a wild guess, I need to collect more debugging
>  output, and analyze it thoroughly.

	Profiling would be able to tell you where BIND is spending most 
of its time.  However, if you were running multi-threaded, I don't 
think that most profiling tools would be able to help.  Nevertheless, 
if BIND was running in multi-threaded mode, other threads should 
continue to answer queries while some threads may be blocked.

>  Is BIND 9 even up the the task of replacing BIND 8 on heavily loaded
>  boxes? From my tests so far, it cannot replace our current public DNS
>  servers, or even caching servers for internal use - due to poor
>  performance.

	All the benchmarks I've seen indicate that BIND 9 should be more 
than adequate to replace BIND 8 nameservers in all roles, with the 
possible exception of root nameservers, and other nameservers seeing 
multiple thousands of DNS queries per second.  And even then, Rick 
Jones has demonstrated that on a properly configured machine, you 
should still be able to handle at least tens of thousands of DNS 
queries per second.

-- 
Brad Knowles, <brad.knowles at skynet.be>

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