OT: Load Balancing & redundancy using Multiple A records

[Joost Waversveld]

Julian Field wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
>
>
> shuttlebox wrote:
>   
>> On Nov 23, 2007 12:13 PM, Steve Freegard <steve.freegard at fsl.com> wrote:
>>   
>>     
>>> It works, but don't expect it to load balance well.  For that you really
>>> do need a proper load-balancer that can examine metrics of each of the
>>> back-end systems and direct connections to them accordingly.
>>>     
>>>       
>> I use this method both on the public (many-to-few) and the private
>> side (few-to-few) of the network and it works real well. Over a months
>> worth of traffic I see a difference of only 1-2%.
>>   
>>     
> Join the club. I use round-robin DNS between a bunch of A records in my 
> single MX record, and it load balances it long-term rather nicely. The 
> web page you referred to talks all about the rules and regs but doesn't 
> really take account of what is actually implemented. Yes, the rules say 
> that DNS imposes no order in the results of a lookup. But in practice 
> the implementers tend to just read in an array and use it in order. So 
> it does help in my experience, whatever the rulebook says.
>
> Just my 2p worth.
>
> Jules
>
> - -- 
> Julian Field MEng CITP CEng
> www.MailScanner.info
> Buy the MailScanner book at www.MailScanner.info/store
>
> MailScanner customisation, or any advanced system administration help?
> Contact me at Jules at Jules.FM
>
> PGP footprint: EE81 D763 3DB0 0BFD E1DC 7222 11F6 5947 1415 B654
> For all your IT requirements visit www.transtec.co.uk
>
>
> -----BEGIN PGP SIGNATURE-----
> Version: PGP Desktop 9.7.0 (Build 867)
> Comment: Use Thunderbird's Enigmail Add-on to verify this message
> Charset: ISO-8859-1
>
> wj8DBQFHRvjSEfZZRxQVtlQRAjT7AJ432f1CicO4Y6ADb5qxL9fxpiUe4gCePdNI
> N/y1uRgSC9MSyERG+j30uj0=
> =cGTe
> -----END PGP SIGNATURE-----
>
>   
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.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.mailscanner.info/pipermail/mailscanner/attachments/20071123/a893ccb0/attachment.html