Re: interop problems with getaddrinfo() address selection

Stephane Bortzmeyer <bortzmeyer@nic.fr> Tue, 11 December 2007 09:47 UTC

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Date: Tue, 11 Dec 2007 10:47:46 +0100
From: Stephane Bortzmeyer <bortzmeyer@nic.fr>
To: Keith Moore <moore@cs.utk.edu>
Subject: Re: interop problems with getaddrinfo() address selection
Message-ID: <20071211094746.GA29759@nic.fr>
References: <200712062020.PAA16213@Sparkle.Rodents.Montreal.QC.CA> <Pine.LNX.4.64.0712071735070.24448@hermes-1.csi.cam.ac.uk> <475B0ABC.5090806@cs.utk.edu> <Pine.LNX.4.64.0712092000150.29087@hermes-1.csi.cam.ac.uk> <475C5047.3010807@cs.utk.edu> <Pine.LNX.4.64.0712100739410.29087@hermes-1.csi.cam.ac.uk> <200712101815.NAA27674@Sparkle.Rodents.Montreal.QC.CA> <Pine.LNX.4.64.0712101935070.24448@hermes-1.csi.cam.ac.uk> <200712102311.SAA01012@Sparkle.Rodents.Montreal.QC.CA> <475DDAA7.3060308@cs.utk.edu>
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On Mon, Dec 10, 2007 at 04:32:39PM -0800,
 Keith Moore <moore@cs.utk.edu> wrote 
 a message of 47 lines which said:

> on the other hand, if the site is trying to do dynamic
> load-balancing with DNS by having DNS favor lightly-used servers,

There is a standard way for a site to do this sort of "DNS
engineering" and it is SRV (RFC 2782). Everything else can be only a
hack since, as explained, the DNS and the subsequent libraries cannot
guarantee anything about the order of addresses.