Maintained by: NLnet Labs

[Unbound-users] Strange lookup error

W.C.A. Wijngaards
Wed Sep 11 15:17:29 CEST 2013


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Hi Mathias,

On 09/11/2013 03:01 PM, Mathias Tauber wrote:
> Hi all,
> 
> we've got here a little problem with resolving single domains. Two 
> examples:
> 
> ~# host www.oas.com www.oas.com is an alias for www.lb.oas.com. 
> www.lb.oas.com has address 200.230.27.19 ;; connection timed out;
> no servers could be reached ;; connection timed out; no servers
> could be reached
> 
> Or:
> 
> ~# host www.lchclearnet.com www.lchclearnet.com is an alias for
> www.wip.lch.com. www.wip.lch.com has address 195.246.229.8 ;;
> connection timed out; no servers could be reached
> 
> Any idea why we get an ip but the lookup itself fails?

The second and third lines in host are for the ipv6 address (AAAA
record) and the mail server (MX record).  These fail with a timeout.
It is likely that the authority server for these domains does not
respond to AAAA and MX records and unbound copies this to you.  If the
authority for these domains answers for AAAA and MX, even if that is
an empty packet without an answer, then you would not get a timeout here.

> Infos about our environment:
> 
> - Ubuntu 12.04 LTS - Unbound v1.4.16-1 - Squid Proxy
> 
> If we try to access these domains through the proxy we get an dns
> error.

It should be able to get the ipv4 address, not sure why it fails.

Best regards,
   Wouter

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