Re: [exim] Potential logic error in retry handling for IPv4+…

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Auteur: Florian Weimer
Date:  
À: Marc Haber
CC: exim-users
Sujet: Re: [exim] Potential logic error in retry handling for IPv4+IPv6 hosts
* Marc Haber:

> This is, btw, not an ipv6 issue exclusively, it might happen in
> ipv4-only setups as well. See Debian Bug #342619 for another example.


I'm not sure if it's the same bug, and I wouldn't be surprised if the
behavior was deliberate in that case (after all, the whole "long
failure period" business is there to generate immediate bounces, so
that users won't have to wait for five days until they are told about
their mistake).

In the example in the bug report, we there are two A RRs:

mailrelay.direct-adsl.nl. 86400 IN      A       195.121.6.12
mailrelay.direct-adsl.nl. 86400 IN      A       195.121.6.56


But resolvers MUST cache the whole set of records and expire them at
the same time. If the resolver fails to do this properly and provides
a wrong view on DNS, there is no workaround on Exim's side.