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Re: [DNSOP] BCP on rrset ordering for round-robin? Also head's up on bind 9.12 bug (sorting rrsets by default)

Tony Finch <dot@dotat.at> Fri, 15 June 2018 16:54 UTC

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Date: Fri, 15 Jun 2018 17:53:57 +0100
From: Tony Finch <dot@dotat.at>
To: Erik Nygren <erik+ietf@nygren.org>
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Subject: Re: [DNSOP] BCP on rrset ordering for round-robin? Also head's up on bind 9.12 bug (sorting rrsets by default)
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Erik Nygren <erik+ietf@nygren.org> wrote:

> A number of folks have been bitten by a bug in bind 9.12 where it silently
> changes the default sorting of rrsets to always be sorted (even if the
> authoritative response wasn't sorted).

Huh, I noticed this and put the workaround in my config but I didn't
realise it counted as a bug.

Anyway, there's a related issue, RFC 3484 address sorting. I believe glibc
used to derandomize addresses in getaddrinfo(), but it seems to have
stopped doing so. (However I can't find a changelog item saying so...)

Windows had a similar issue (I think it was fixed in Windows 7?):

https://support.microsoft.com/en-us/help/968920/windows-vista-and-windows-server-2008-dns-clients-do-not-honor-dns-rou

I never understood how RFC 3484 sorting could possibly make sense when
there's no way for an edge device (or even an expert sysadmin) to know
anything meaningful about how IP addresses relate to network topology.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
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