multiple CNAMEs revisited
CS
google at fasttrackmonkey.com
Tue May 25 23:49:15 UTC 2004
This is a testy subject, and I'm fully aware that what I want/need to
do is not allowed.
That said, I need to replicate the following "bogus" configuration:
spamd IN CNAME spamd1
spamd IN CNAME spamd1
spamd IN CNAME spamd2
spamd IN CNAME spamd2
spamd IN CNAME spamd3
spamd IN CNAME spamd4
spamd1 IN A 10.0.0.1
spamd2 IN A 10.0.0.2
spamd3 IN A 10.0.1.1
spamd4 IN A 10.0.1.2
This hack let you work around BIND collapsing identical A records. If
it's not obvious, I'm working with a spamassassin cluster, and spamc
with the above dns hackery and a local copy of dnscache with the
round-robin patch currently splits the load between two servers very
well. And it solves the "what if a server is down" problem by just
trying the next server in line if it doesn't get a response.
root at helga[/tmp]# grep "spamd1 spamd" /var/log/spamd|wc -l
20872
root at helga[/tmp]# grep "spamd2 spamd" /var/log/spamd|wc -l
20870
I need to add two more smaller servers to this cluster, so I'd like to
alter the weighting in DNS. Again, I understand DNS is not meant to
solve these problems, but in this case, it could solve them very well
if the above config was legal (or if there was a config option to
allow the "illegal" behaviour).
So given the current constraints, what is a good workaround? I've
looked at load-balancing tools, and frankly this is a better solution;
I don't want to rely on one piece of software; DNS in this case has a
good deal of built-in redundancy.
If this is not feasible with bind, are there any other servers I
should be looking at?
Thanks,
Charles
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