Re: split the load?

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Author: Nigel Metheringham
Date:  
To: Piete Brooks
CC: tron, exim-users
Subject: Re: split the load?
OK, let see if I can summarise to date....

- Exim currently uses A/MX records in the order returned from the DNS
(MXs being pref sorted).

- Bind can round robin A records.

- It is an advantage to the receiving site to have incoming round robined
(effectively randomised) to balance loading.

If you run a local copy of bind (or your favourite DNS server) on the mail
server box (caching only - I suppose you could run an authoratative server
on the mail box, but with bind's hate of anyone else using system memory
this may not be a good plan :-) ), then you can get the A records
randomised for any name.

However I guess that if you have a set of MX records with equal preference
then they should be used in a random order, and the DNS doesn't do this
for you.

So even if we decide that the A record issue can be punted to bind, the MX
record issue cannot, in which case we might as well implement both...
(hows that for circular arguments).

[My copy of the source is off line right now so I haven't looked this up]

    Nigel.


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[ Nigel.Metheringham@???   - Unix Applications Engineer ]
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