Re: [exim] DNS Question

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著者: Marc Perkel
日付:  
To: Fred Viles
CC: exim-users
題目: Re: [exim] DNS Question
I think this will work - thanks.

I ran this:

dig yahoo.com mx

It returns 4 MX records and each one returns multiple IP addresses.

Fred Viles wrote:

>On 7 Jan 2005 at 16:24, Marc Perkel wrote about
>    "[exim] DNS Question":

>
>| How do you set up an A record to return more than one IP address?
>
>"An" A record contains one IP address, by definition. But you can
>have any number of A records owned by the same name. Any type=A
>query for the name will return the entire matching set of A records
>(just like MX records and most other record types).
>
>| When it
>| is set up this way - does it return ALL the IP addresses or randomly
>| just one of the list? or is that configurable.
>
>All, in no particular order.
>
>| I have this idea for front end spam filtering servers in diverse
>| geographic locations, all on the same name so that the email might go
>| randomly to any one of these servers and then funneled securely to the
>| "real" server where it is read by the end users.
>|
>| So - can I do this?
>
>Sure. You can have multiple MX records having the same priority
>value, and each of the MX name values can own multiple A records.
>
>I would recommend multiple MX rather than multiple A. You can't rely
>on the SMTP clients to notice that there is more than one A record,
>which matters if one or more of the hosts is down or unreachable.
>
>- Fred
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