OT: Load Balancing & redundancy using Multiple A records

Steve Freegard steve.freegard at fsl.com
Fri Nov 23 16:38:46 GMT 2007

Richard Frovarp wrote:
> shuttlebox wrote:
>> On Nov 23, 2007 5:08 PM, Joost Waversveld <joost at waversveld.nl> wrote:
>>>  Ya, maybe, but the DNS does not look at the load of the machines.
>>>  If you're mailservers are all exactly the same with hardware, etc. 
>>> then it
>>> will be a good solution. Otherwise you will get problems.
>> Not really, if one implements throttling in the MTA a denied
>> connection means the next MX will be tried so if one server gets
>> exhausted quickly the more powerful one will get more traffic by using
>> the fault tolerance part of the protocol. Pretty cool to get both load
>> balancing and fault tolerance without either effort or cost.
> Yeah, but will the sending SMTPs fail through the multiple A records for 
> a single MX?

Varies greatly by MTA - some will and some won't.  Best to have at least 
two MX records as I originally specified for this reason.

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