Question about how forwarders work

Barry Margolin barmar at alum.mit.edu
Tue Dec 16 15:47:18 UTC 2014


In article <mailman.1284.1418722463.26362.bind-users at lists.isc.org>,
 Richard Thomas <Richard.Thomas at the-logic-group.com> wrote:

> Hi all,
> 
> Having heard about recursion, is there a way of getting BIND to make 
> recursive DNS requests to the A.B.C.D and E.F.G.H DNS servers?

Requests to forwarders always have the Recursion Requested flag set. So 
you could point them to your ISP's resolvers if you wanted.

> 
> Thanks,
> 
> Richard Thomas.
> 
> 
> -----Original Message-----
> From: bind-users-bounces at lists.isc.org 
> [mailto:bind-users-bounces at lists.isc.org] On Behalf Of Matus UHLAR - fantomas
> Sent: 11 December 2014 16:39
> To: bind-users at lists.isc.org
> Subject: Re: Question about how forwarders work
> 
> On 11.12.14 16:28, Richard Thomas wrote:
> >Please could I have some advice about how the below example configuration 
> >would work:
> >
> >forwarders { A.B.C.D; E.F.G.H; };
> >
> >What I wanted to achieve is that one of the IP addresses to be used as 
> >a  primary DNS server and the other IP address to be used as a 
> >secondary DNS  server.
> 
> BIND measures RTT for servers and uses the one that answes faster.
> It ocasionally re-tries slower server, if the situation did not change.
> That should result to fastest resolution. This should be the best for you.
> 
> Many people recommend doing recursion directly instead of using forwarders.
> Especially for mail servers with anti-spam measures, where your forwarders 
> may be ignored by some blacklists, because they send too much queries.
> 
> --
> Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
> Warning: I wish NOT to receive e-mail advertising to this address.
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-- 
Barry Margolin
Arlington, MA


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