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Old 06-21-2012, 07:54 AM
Umarzuki Mochlis
 
Default round-robin mx and nginx proxy

I need general help on a multi-server setup with

2 MTAs (each also a nginx reverse-proxy)
2 mailbox servers (round-robin)

when i check nginx.log on both MTA, only the second MTA got https
connection (zimbra support also confirmed this) and it seems that this
might caused by DNS setup or related network configuration

how do I pinpoint as to where the root cause might be?
--
Regards,

Umarzuki Mochlis
http://debmal.my


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Old 06-21-2012, 10:30 AM
Darac Marjal
 
Default round-robin mx and nginx proxy

On Thu, Jun 21, 2012 at 03:54:28PM +0800, Umarzuki Mochlis wrote:
> I need general help on a multi-server setup with
>
> 2 MTAs (each also a nginx reverse-proxy)
> 2 mailbox servers (round-robin)
>
> when i check nginx.log on both MTA, only the second MTA got https
> connection (zimbra support also confirmed this) and it seems that this
> might caused by DNS setup or related network configuration
>
> how do I pinpoint as to where the root cause might be?

I think I would first start by checking the output of repeated calls to
"dig +short mx yourdomain.example.org". This should vary, with your
servers swapping positions each time.

If you only get the same output each time, then it's down to the sending
MTA to pick an appropriate MX from the list. I assume both your MXs have
the same priority; in that case the sending SMTP should pick one at
random and, if that fails, try the other. Note here, that if you're
using round-robin AND same-priority MXs, both are picking the order at
random.


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Old 06-22-2012, 02:29 AM
Umarzuki Mochlis
 
Default round-robin mx and nginx proxy

2012/6/21 Darac Marjal <mailinglist@darac.org.uk>:
> On Thu, Jun 21, 2012 at 03:54:28PM +0800, Umarzuki Mochlis wrote:

> I think I would first start by checking the output of repeated calls to
> "dig +short mx yourdomain.example.org". This should vary, with your
> servers swapping positions each time.
>
> If you only get the same output each time, then it's down to the sending
> MTA to pick an appropriate MX from the list. I assume both your MXs have
> the same priority; in that case the sending SMTP should pick one at
> random and, if that fails, try the other. Note here, that if you're
> using round-robin AND same-priority MXs, both are picking the order at
> random.
thanks,

i also need to know how I would be able to investigate the flow of
emails. What I had tried so far:

dig +short mx reveals that from outside, users would hit barracuda MTA first
then barracuda would forward (or so i thought) to a MailScanner
(barracuda's outbound smtp host setting)

but how do I check that MailScanner (installed on top of centos 5)
forwards emails to those 2 MTA+proxy servers?

email system is working at the moment, fortunately.

mail flow that i assumed from outside:
user -> barracuda -> mailscanner -> second zimbra MTA+proxy server ->
one of two mailbox servers (via its public name)

thanks

--
Regards,

Umarzuki Mochlis
http://debmal.my


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Old 06-22-2012, 03:43 AM
Richard Hector
 
Default round-robin mx and nginx proxy

On 21/06/12 22:30, Darac Marjal wrote:
> On Thu, Jun 21, 2012 at 03:54:28PM +0800, Umarzuki Mochlis wrote:
>> I need general help on a multi-server setup with
>>
>> 2 MTAs (each also a nginx reverse-proxy)
>> 2 mailbox servers (round-robin)
>>
>> when i check nginx.log on both MTA, only the second MTA got https
>> connection (zimbra support also confirmed this) and it seems that this
>> might caused by DNS setup or related network configuration
>>
>> how do I pinpoint as to where the root cause might be?
>
> I think I would first start by checking the output of repeated calls to
> "dig +short mx yourdomain.example.org". This should vary, with your
> servers swapping positions each time.
>
> If you only get the same output each time, then it's down to the sending
> MTA to pick an appropriate MX from the list. I assume both your MXs have
> the same priority; in that case the sending SMTP should pick one at
> random and, if that fails, try the other. Note here, that if you're
> using round-robin AND same-priority MXs, both are picking the order at
> random.

Wait - is this https or SMTP? MX records will only affect SMTP, and the
question seemed to relate to https. I got the impression that the fact
that the servers also ran MTAs was incidental.

Still, the issue will relate to what IP address comes back from a query,
and how long it's cached by the client (and intervening name servers).

Richard


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Old 06-25-2012, 08:38 AM
Umarzuki Mochlis
 
Default round-robin mx and nginx proxy

2012/6/22 Richard Hector <richard@walnut.gen.nz>:

>
> Wait - is this https or SMTP? MX records will only affect SMTP, and the
> question seemed to relate to https. I got the impression that the fact
> that the servers also ran MTAs was incidental.
>
> Still, the issue will relate to what IP address comes back from a query,
> and how long it's cached by the client (and intervening name servers).
>

it seemed that i had asked a wrong question

this concerns more on the reverse-proxy by provided by nginx that
supposed to load-balance between 2 reverse-proxe servers which
coinidentally MTA servers


--
Regards,

Umarzuki Mochlis
http://debmal.my


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Old 06-25-2012, 08:40 AM
Umarzuki Mochlis
 
Default round-robin mx and nginx proxy

2012/6/25 Umarzuki Mochlis <umarzuki@gmail.com>:
> 2012/6/22 Richard Hector <richard@walnut.gen.nz>:
>
>>
>> Wait - is this https or SMTP? MX records will only affect SMTP, and the
>> question seemed to relate to https. I got the impression that the fact
>> that the servers also ran MTAs was incidental.
>>
>> Still, the issue will relate to what IP address comes back from a query,
>> and how long it's cached by the client (and intervening name servers).

> it seemed that i had asked a wrong question
>
> this concerns more on the reverse-proxy by provided by nginx that
> supposed to load-balance between 2 reverse-proxe servers which
> coinidentally MTA servers

my bad, that supposed to go like this:

this concerns more on the reverse-proxy by provided by nginx that
supposed to be load-balanced between 2 reverse-proxy servers which
coincidentally are MTA servers.


--
Regards,

Umarzuki Mochlis
http://debmal.my


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