Arthur Sherman [mailto:arturs (at mark) netvision.net.il] said:
>
> Assume we co-locate our servers at different ISPs, say bezeqint.net and
> netvision.net.il
> Both ISP, obviously, have different IP scopes, let's call them net1 and
> net2.
>
> So, 1st mx sits in net1, and 2nd - within net2.
> Both mx share same hostname but have different IP.
>
> Now, assume that a customer's comes from net1.
> I'd like him to always choose 1st mx, unless it's down, then it switches
> to
> 2nd mx.
>
> I think that a problem here would be syncronization of mailboxes.
> Or, am I wrong?
I think you are confusing MX with mail host.
When I talk about an MX, I'm talking about the DNS type "MX" (Mail
eXchanger). This is only ever used by MTA's (mail servers) when delivering
mail to a domain.
I think what you are talking about is which mail host to point your users at
for reading / sending mail, which is entirely different. Even if they are
the same machines, it's still different things. End users don't care about
MX's. Only mail servers care about MX's.
Do the two ISP's act as secondary DNS's for your domain (the one with the
MX's in it)?
If you are trying to hand out different IP's for 'mail.yourdomain.com' (or
whatever hostname your customers use for reading/sending mail) depending on
which network they are on, you'll either have to have slightly different
zone files at each ISP, or (if you are the only authoritative DNS for your
zone) you'll need to use one of the various DNS extensions which allow
'intelligent' resolution determined by the IP of the client ... exactly how
you do that will depend on what DNS software you run.
> Arthur Sherman
> 052-4878851
-- hugh