Sam Varshavchik wrote:
Rodrigo Severo writes:
Sam Varshavchik wrote:
The DNS server already returns DNS records in random order.
I believe that by "random order" you mean a different random order
for each query. If this is the case I would like to ask to which DNS
servers do you refer specifically?
Anyone heard of "bind"?
Yeah. Sure...
Could you please advise on how can I get a more random MX choosing by
Courier?
Stop using broken DNS caches.
That's not exactly what I wanted to hear but I can live with it.
By definition, the only function of a cache is to speed up lookups.
An application that uses a cache, be it a DNS cache, a web cache, or
any other kind of cache whatsoever, should NOT be aware that it's
using a cache, and not the real thing. It should get the same reply
that it would get from the real thing. Except that it would get the
reply faster.
Therefore, it is the caching software's complete and full
responsibility to behave and act in every way like the real thing,
except that it's faster.
Does anybody knows of any suitable solution for this issue besides bind?
I want by all means not to go back using bind if at all possible.
Real DNS servers return record in random order. Therefore, a properly
implemented cache will also return records in random order. If it
doesn't, it's broken and it needs to be fixed.
Let me suggest that this issue get some explicit treatment in Courier's
documentation. Something like the following observation:
------------------------------------------------------------------------------------------------------------------------------
Courier relies in the randomness of the internal order of the DNS
replies it gets for better load balancing and reliability during message
delivery.
Known non-random (not siutable) DNS caches:
DJB's dnscache;
glibc's nscd.
Known random (suitable) DNS caches:
bind.
------------------------------------------------------------------------------------------------------------------------------
Thanks again for your clarifications,
Rodrigo Severo
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