Re: DNS not resolving mail server for ADSL users

From: Kevin D. Goodknecht [MVP] (admin_at_nospam.LSAOL.COM)
Date: 03/21/04 

Date: Sun, 21 Mar 2004 02:50:54 -0600

In news:10b8d01c40efb$423de7f0$a301280a@phx.gbl,
the confused <anonymous@discussions.microsoft.com> posted a question
Then Kevin replied below:
> ha, here is Kevin!
>
> did I say my intention was to confuse, see my name!
> (Sorry jennie)
>
> Clients do not need to look up MX records, that's
> correct..however, firewall rules may need the MX record
> to identify mail servers, so it better to set up one as
> an identifier.
>
> In addition, the following statemnet is confusing:
>
> "You don't need an MX record in an internal zone, only
> SMTP servers look for MX records and there should be no
> SMTP servers looking at the internal zone. I can't think
> of even one SMTP server that will be looking for an MX
> record for a mail domain it hosts."
>
> If you have more than one internal domain and each domain
> has SMTP servers, you do need MX records for the SMTP
> servers.
>

Maybe the way you configure your mail servers, there is no need for internal
MX it only confuses the issue. The issue was resolving the mail server host
name by the clients.

Incidentally internal mail servers should need MX records each mail server
should be configured so they know which mail server hosts the mail boxes for
all internally hosted domains.

But using you scenario, since I host ten mail domains on three SMTP servers
I should have MX records internally?
Sounds like a waste of DNS bandwidth to me, all mail servers are under my
control why should I want to configure them to check with DNS for mail
domains I know where to relay to. Each internal SMTP server should be able
to accept mail for any of the ten domains I host, then the SMTP server is
configured so that it knows which server to relay the mail to for
distribution. This is done without MX records, it is in the configuration. I
do this for redundancy, all three SMTP server can accept mail for each of
the ten domains. 

-- 
Best regards,
Kevin D4 Dad Goodknecht Sr. [MVP]
Hope This Helps
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