Re: [exim] DNS problems with sending via multiple smarthosts

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Author: Evgeniy Berdnikov
Date:  
To: exim-users
Subject: Re: [exim] DNS problems with sending via multiple smarthosts
On Fri, Jul 19, 2019 at 03:12:38AM -0400, Viktor Dukhovni via Exim-users wrote:
> Actually, the "tcpdump" documentation is misleading. In the attached
> PCAP file (single outbound query), "tcpdump" reports "[1au]", but the
> query has no authority records, rather it has an EDNS(0) OPT record:


Thank you for explanation, Viktor.

> If there were a simple way to get the stub resolver to set only
> the AD bit, Exim could use that, and you'd not run into this
> particular obstacle, but the fault is wither whatever device
> is filtering your DNS queries. It is b0rked, and it would
> be good to find a way to get it to stop doing that.


Yes, I've looked through David Purton's dump again and catch that
broken dns answers are arrived with ttl=64 and ip id equal to ip id
of client packets, while google's anwers come with ttl=116-117 and
random ip ids, as it should be for large computing farm behind
load balancer. So dns mangling is probably performed on WiFi AP.
--
Eugene Berdnikov