Round-Robin for mail/smtp hosts
Brad Knowles
brad.knowles at skynet.be
Wed Jul 4 09:05:10 UTC 2001
At 7:31 PM -0700 7/3/01, Matt Prigge wrote:
> What I am most curious about is how the clients (OE/Netscape/etc) implement
> failover using multi-A RRsets.
They don't. They latch onto the first IP address they are told,
and they will never, ever try a different one (no matter how many
times you have them re-query for correct information) until they are
rebooted.
> Is it handled by the underlying OS?
In my experience, it's not handled at all. It should be handled
by the OS, but it simply isn't.
> Or is it
> the client really responsible for trying the first RR and then, if that
> fails, trying subsequent RRs out of the same set?
There may be clients out there that have been written to by-pass
this problem within Microsoft OSes, but I have never personally
experienced any.
> Do some clients not do
> this?
I have not yet encountered a client on a Microsoft OS that goes
to this length.
> This scheme seems like it will work well as a low-grade form of load
> balancing, but how well will it work as far as redundancy is concerned?
In my experience, it won't.
--
Brad Knowles, <brad.knowles at skynet.be>
/* efdtt.c Author: Charles M. Hannum <root at ihack.net> */
/* Represented as 1045 digit prime number by Phil Carmody */
/* Prime as DNS cname chain by Roy Arends and Walter Belgers */
/* */
/* Usage is: cat title-key scrambled.vob | efdtt >clear.vob */
/* where title-key = "153 2 8 105 225" or other similar 5-byte key */
dig decss.friet.org|perl -ne'if(/^x/){s/[x.]//g;print pack(H124,$_)}'
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