Using multiple A records is good for performance balancing, but what if one of 
the systems fails? 

Using your cocnfiguration, the delivering mail server has an "a" record and a 
single MX, so it wouldn't try the other mail server in the case of a failure, 
right? 

Whereas, by listing multiple IPs and mx1/mx2, wouldn't the delivering mail 
server try the other address? 

Thanks, 

-Ben 

On Tuesday 25 October 2005 16:02, you wrote:
  

I once did this and it worked great:

     IN    MX    10 mx.example.com.

mx   IN    A    192.168.1.1
     IN    A    192.168.1.2

...etc.  Perfect DNS load balancing.

Jack

Benjamin Smith wrote:

    

Currently, we have two mail relays for inbound messages, and a third for 
      

POP.
  

The inbound messages go thru all the CPU-intensive anti-spam stuff, and 
      

then
  

they relay it to the POP server for pickup.

Currently, one of these is the "primary", and the other is "secondary", and
I'd like them to be considered more or less as equals, since the "primary"
system is getting beaten pretty hard.

The DNS zone file says something like this:

###############################
@isp.com
<SNIP>
               IN      MX      100 mx1.isp.com.
               IN      MX      1100 mx2.isp.com.
<SNIP
################################

I seem to recall that I make them act as "equals" by simply changing this 
      

to
  

###############################
@isp.com
<SNIP>
               IN      MX      100 mx1.isp.com.
               IN      MX      100 mx2.isp.com.
<SNIP
################################

so that they both get about the same amount of inbound messages. Has 
      

anybody
  

here actually done this? How well does this work as far as failover if 
      

either
  

system fails?

-Ben
--
"The best way to predict the future is to invent it."
- XEROX PARC slogan, circa 1978
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