Max traffic inbound bind cap?. Absolutley bizzarie.

[Mark Andrews]

> Hello there, we currently have 2 recursive resolvers running SOL9 and
> Bind 9.3.0 that is preplexing me to no end and I'm sincerly hoping
> someone can point me in the right direction as I'm near my wits end. 
> Our customer state theyocassionaly has to reload the web page to have
> it resolve properly.
> 
> The named.conf is pretty basic.
> 
> options {
>         directory "/opt/apps/bind-9.3.0/";
>         pid-file "/var/adm/named930.pid";
>         statistics-file "/var/adm/named.stats"; 
>         dump-file "/var/adm/named_dump.db";
>         minimal-responses yes;
>         recursive-clients 2000; 
>         notify no;
> };
> 
> 
> These machines are customer facing and see about 4 million queries an
> hour or about 70,000 a min.  The majority of these about 45,000 being
> A record lookups.
> 
> My MRTG graph is showing that the upper limit on inbound traffic to
> these servers is 2.11 M a second and at times here's the weird part
> it's sporadic and inconsistent that it can tqake as long as 2 to 5
> seconds to resolve a lookup.  Is there a limit on the inbound traffic
> that bind accepts?  What would be capping this?  I'm pretty perplexed
> about this because it simply doesn't make sense to me.  I don't
> believe it to be a network issue, the interface are full 100.

	Do your caches have IPv6 connectivity to the A.GTLD-SERVERS.NET
	and B.GTLD-SERVERS.NET?  There is a bug (fixed in 9.3.1/9.2.5)
	which makes the first lookup to a new COM/NET site slow.

	Upgrade to the current rc's or specify -4 on the command line.
 
> I would really appreciate any thought or pointers, even constructive
> critisim at this point that would lead me to a solution.  Is it
> possible that bind is maxing out it's open sockets that it accepts
> traffic on?
> 
> Many thanks in advance.
> 
> B
> 
> 
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org