LinuxSA Mailing list archives

  From: Daryl Tester <Daryl.Tester@iocane.com.au>
  To  : Adam W <woja@optushome.com.au>
  Date: Sun, 29 Apr 2001 20:29:51 +0930

Re: Dyn DNS and sendmail

Adam W wrote:

> What should i be adding. The hostname allocated to me by my ISP - this being
> co3002884-a.???.???.optushome.com.au

You could, but this may be fraught with danger.  Bear in mind that I
don't know how the mechanics of dyndns works, but I'm guessing that
everytime you log on (presuming you're using a dial up connection)
then you register your current hostname with dyndns.  Do you remove
your MX record before you log off?  If you don't, and you're not
assigned a static IP address (ie, the IP address is dynamic and
belongs to a dialin pool) then there is a good chance that it will
get assigned to someone else on dialin - either your email will
get fed into a host that doesn't have SMTP running, or worst case
is that it does have SMTP running and either rejects (bounces) or
accepts (your email disappears)

Conversely, if you do remove the MX entry, then MTA's that send you
email while you're not online may reject sending you email because
you don't have a valid MX entry; there certainly wasn't a backup MX
listed when I checked before (and it would suffer from the same
problem trying to deliver to you).

I believe the dyndns sort of services are usually for people who are
"mostly on", but have shifting IP addresses (possibly due to ADSL or
the like) - even then, there is a small (ie greater than zero) chance
that their email may wind up on someone else's MTA while they're in
the process of moving IPs.

> Or the Hostname:
> 
> woja.ath.cx
> 
> or the IP allocated to me by my ISP?

I think what you're trying to achieve is to have the MX point to
to woja.ath.cx, and update woja.ath.cx's IP address when you're
online.  But beware the caveats.

> Feel free to correct my terminology.

"I do not think that means what you think that means."

-- 
Regards,
  Daryl Tester,  Software Wrangler and Bit Herder, IOCANE Pty. Ltd.

"You shouldn't mix meditation with management.  The mind gets too empty."
  -- Dilbert

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