MX Record Theories

Alex H. Ryu r.hyunseog at ieee.org
Tue May 26 13:42:39 CDT 2009


I don't think there is no real answer for your question.
It depends on each company's business objective, the cost, network
topology, and their policy.
MX record is the the mechanism for mail delivery procotol.
It doesn't dictate how to implement.
Depending on mail volume, and network policy, you can implement actual
mail servers within DNS/SMTP protocol.

There are multiple ways to get things done.
Depending on budget, business objective, network resource/policy,
you can choose the way that fits to your need.

It is same as Microsoft Windows operating system.
Microsoft release the Windows, but it doesn't say you have to run it as
cluster or not.
Depending on your need, and your own analysis/decision, you can run
whatever you like.


Alex


gb10hkzo-nanog at yahoo.co.uk wrote:
> Hello all,
>
> First, I hope this is not off-topic for NANOG, please be gentle with me as this is my first post.
>
> I
> would be most interested to hear NANOG theories on the variety of MX
> record practices out there, namely, how come there seem to be so many
> ways employed to achieve the same goal ?  Do you have experience in
> more than one of these methods and which do you favour ?
>
> To illustrate my question :
>
> (1)
> If you query the MX records for, Hotmail or AOL you will receive 4
> equal weight MX records, each of the MX records having a round-robin
> set of IPs.
> e.g.
> hotmail.com.        2706    IN    MX    5 mx4.hotmail.com.
> hotmail.com.        2706    IN    MX    5 mx1.hotmail.com.
> hotmail.com.        2706    IN    MX    5 mx2.hotmail.com.
> hotmail.com.        2706    IN    MX    5 mx3.hotmail.com.
> -and-
> mx3.hotmail.com.    1926    IN    A    65.xxxxxxx
> mx3.hotmail.com.    1926    IN    A    65.xxxxxxx
> mx3.hotmail.com.    1926    IN    A    65.xxxxxxx
> etc.etc.
>
> (2)
> Alternatively, some people, particularly the ones that use hosted
> filtering, tend to have one MX record, which as multiple round robin
> IPs.
> e.g.
> microsoft.com.        780    IN    MX    10 mail.global.frontbridge.com.
> -and-
> mail.global.frontbridge.com. 1728 IN    A    65.xxxxxxx
> mail.global.frontbridge.com. 1728 IN    A    207.xxxxxxx
> etc. etc.
>
> (3) And others simply have a more traditional setup using multiple MX records and only one IP per MX record with no round robin
> apple.com.        931    IN    MX    10 mail-in14.apple.com.
> apple.com.        931    IN    MX    20 mail-in3.apple.com.
> apple.com.        931    IN    MX    20 eg-mail-in2.apple.com.
> etc.etc.
>
>
> So
> what's the big deal ?  Please note I'm not asking which is "better" ...
> I am just curious and interested to hear your professional opinions and
> experiences.
>
> Personally, I favour the simple option 3, multiple MX records.
>
> Thanks y'all.
>
>
>       
>
>
>
>
>   





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