Re: Redundant mail server
On Sun, 13 Feb 2005 23:01:30 -0800, Curtis Vaughan <curtis@npc-usa.com> wrote:
> >>> You can add to the your DNS zone configuration any number of mail
> >>> servers (0,1,2,3 is the priority, it will try 0, then 1, then 2 ...):
> >>>
> >>> IN MX 0 mailUS.example.com.
> >>> IN MX 1 mailCH.example.com.
> >>> IN MX 2 mailBR.example.com.
> >>> IN MX 3 mailUK.example.com.
> >>>
> >>> I don't know how to configure the backup mail server to send the
> >>> backed up mails to the main server when it is up again.
> >>>
> >> Oh, I forgot to say that the assumption here is that all possible
> >> internet connectivity with the US office is down. So there would be no
> >> way to basically repoint incoming mail to any other server.
> >
> > Ok, I guess you want to have a backup mail server for npc-usa.com and
> > the backup partner could be vostok1.com or vostok.pt or any other:
> >
> > You have to have this configuration on your DNS zone at npc-usa.com:
> >
> > IN MX 10 smtp.npc-usa.com.
> > IN MX 20 mail.vostok1.com.
> >
> > you will also have to configure the mail server at vostok1.com to
> > accept mail relay for npc-usa.com.
> >
> > You don't care if your internet connectivity is down, any mail servers
> > trying to send mail to you will query the DNS server at speakeasy.net,
> > and will find that mail.vostok1.com also accept mail for npc-usa.com.
> >
> >
>
> What you propose is very interesting. Perhaps the solution will be a
> little bit different though.
>
> In the US we host mail.npc-usa.com (and smtp.npc-usa.com),
> mail.vostok1.com (and smtp.vostok1.com).
> The vostok1.com server is the one in question actually. The 2 are
> totally separate servers.
>
> Now let's say for whatever reason the mail servers in our company are
> all down as there is no Internet connectivity with our office.
>
> If I understand correctly I could set up yet another backup domain
> name: let's say vostok.pt.
>
> Regardless of what I have set up internally, I would also have to
> inform speakeasy that any mail intended for mail.vostok1.com should
> also be sent to mail.vostok.pt?
Then you have three different machines!! Good !!!
You can have 3 mail servers backing up each other!!!
Ask speakeasy to:
For npc-usa.com:
add an MX entry with priority 20 pointing to mail.vostok.pt
add an MX entry with priority 30 pointing to mail.vostok1.com
For vostok1.com:
add an MX entry with priority 20 pointing to mail.vostok.pt
add an MX entry with priority 30 pointing to smtp.npc-usa.com
Ask to the provider of vostok.pt:
add an MX entry with priority 20 pointing to smtp.npc-usa.com
add an MX entry with priority 30 pointing to mail.vostok1.com
And that's it (from the DNS side).
> I would therefore have mail.vostok.pt pointed to the overseas
> operations mail server ip address?
Don't worry about IP addresses it will resolve automatically.
It will work this way:
1.- I send a mail to you@npc-usa.com
2.- my mail server receive the mail
3.- my mail server ask the DNS server who handle the mail for npc-usa.com?
4.- the DNS server reply:
with priority 10: smtp.npc-usa.com
with priority 20: mail.vostok.pt
with priority 30: mail.vostok1.com
(also the DNS server will reply the corresponding IP addresses of the 3 servers)
5.- so my mail server first will try to send the mail to the server
with lowest priority, smtp.npc-usa.com, hey but it is down!!!
Then my mail server will try to send the mail to mail.vostok.pt and it
is up!!!! So the mail is sent succesfully.
Or, if mail.vostok.pt is down, it have another chance, it will try to
send it to mail.vostok1.com.
If all are down, it will try later, several times.
6.- If the mail server at vostok.pt is configured properly, it will
send the mail to smtp.npc-usa.com when it goes up. The same apply if
the receiver server was mail.vostok1.com
> Would then any mail sent to mail.vostok1.com also be sent to
> mail.vostok.pt?
No, it will send it to one server not both.
>
> This is an interesting issue that I didn't know existed and appreciate
> any input.
>
> Curtis
>
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--
--Nicolas
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