Maintained by: NLnet Labs

[Unbound-users] Can't resolve m.facebook.com

W.C.A. Wijngaards
Fri Feb 10 14:54:41 CET 2012


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Hi Stephane,

On 02/10/2012 02:42 PM, Stephane Bortzmeyer wrote:
> On Thu, Feb 09, 2012 at 08:29:42AM +0100,
>  Attila Nagy <bra at fsn.hu> wrote 
>  a message of 269 lines which said:
> 
>> It seems the problem is that facebook DNS servers time out on AAAA
>> records, so unbound gets the false assumption that they are
>> unavailable.
> 
> I would say "unbound gets the correct assumption that they are
> out-of-order".
> 
> http://status.aa.net.uk/apost.cgi?incident=1392

An update to looking at unbound's code.  The log excerpt previously has
some code-paths printed out that are impossible; from the code this
output should not be possible.  That indicates trouble at compiletime;
however, there is no resolution on this.

Additionally, in unbound's svn trunk, there is a patch that unlinks A,
AAAA, and other-type timeouts.  Thus if AAAA lookups timeout, then A
lookups will still cause a query to be sent out.  (up to a small limit,
enough to catch these cases as working, but very small for the qps to
actual offline servers).

Best regards,
   Wouter
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