[43371] in North American Network Operators' Group
Re: dns based loadbalancing/failover
daemon@ATHENA.MIT.EDU (Paul Vixie)
Sun Oct 7 13:01:36 2001
To: nanog@merit.edu
From: Paul Vixie <vixie@vix.com>
Date: 07 Oct 2001 10:01:12 -0700
In-Reply-To: ahu@ds9a.nl's message of "7 Oct 2001 03:36:01 -0700"
Message-ID: <g3d73zbd0n.fsf@as.vix.com>
Errors-To: owner-nanog-outgoing@merit.edu
> The way to go about this is to see if breaking existing practice will break
> current implementations and plausible future implementations.
Allow me to apologize, once again, to Microsoft. In the NT 3.5.1 resource kit
they shipped a DNS server which had to do its zone transfers one record per
message since "existing practice" and "current implementations" meant BIND4
which knew no other way. Fortunately we didn't write a BCP describing BIND4's
deviant behaviour, but rather, fixed it in BIND8 and beyond.
> > If that's not the case, though, consider that a correct implementation of
> > DNS would be within its rights to take note of the "same serial number but
> > incoherent answers" condition and declare the zone unreachable. I'm not
>
> Would be pretty silly, and overstepping the robustness principle.
Whether behaviour is robust enough to be called a BCP or not is fodder for a
detailed analysis amongst people who *want* to study and debate such things.
That mailing list, for DNS, is called namedroppers@ops.ietf.org. (Not NANOG.)
> So by your logic, by making sure that the serial numbers never match, we
> would 'unbreak' the situation? Seems like a step in the wrong direction.
There is, simply is and we're not going to argue about it, an identity mapping
between a zone's contents and a zone's serial number. If you don't like that
then you should find a way to change it. Which direction is "wrong" is better
discussed on namedroppers@ops.ietf.org than here.