[lug] MX records in DNS

[Hugh Brown]

Turns out I needed to tell mail.host.dom to accept mail addressed to
web.host.dom

Thanks for the help.

Hugh


On Tue, 2001-12-18 at 18:35, David Morris wrote:
> First, I should clear up some mis-information in previous replies:
> 
> 1) If a host name is not provided, the previous host *is* inherited.  I do
> this for my DNS records, so I guarantee it works.  That is simply the way
> the DNS system is designed, at least assuming a properly functioning
> DNS server...
> 
> 2) the host "web.host.dom" does not need a SMTP server.  What is happening,
> however, is that an MX record does *not* change the host name on email,
> merely the server the email is sent to.  Thus, your mail server at
> "mail.host.dom" must accept email directed to the domain "web.host.dom",
> frequently also including virtual address mappings from the domain
> "web.host.dom" to local users.  In your specific examply, any email sent to
> "hugh at web.host.dom" will still go to "hugh at web.host.dom", but it will be
> *received* by the *server* "mail.host.dom", which will accept or reject the
> message depending on if the mail server is setup to accept or reject that
> particular domain name.
> 
> Number 2 above might be your problem....you would receive an error out of
> email if your mail server is rejecting mail for "web.host.dom".
> 
> In your DNS record, I do see one discrepancy....don't know it is exactly a
> problem, but possibly.  Usually, the MX record priority is a number above
> zero, normally an multiple of 10.  This simply allows for flexibility in
> future changes.  For instance,  my MX records for one domain:
> 
> ---
> 
> ; Mail Server Defaults
>             IN  MX      10 mail
>             IN  MX      20 mail2
> 
> ---
> 
> In the above, note also that I use these settings as defaults for the
> entire record.  They appear just after NS records, which in turn are just
> after the SOA record in my file.  Again, I don't know if this is a problem,
> might just a violation of common convention.
> 
> If you are still having problems after taking all of the above into
> account, send log files from (a) your mail server when you send a message
> (if it shows any entries in the log), (b) your mail client (the exact reply
> you get from a mail server, or the error message given), and (c) your DNS
> server when it is first started.  These should show where the problem is
> occuring.
> 
> Also, be certain you are remembering to update the serial number each time
> you make a change to the DNS record...can't tell you how many times I've
> been bitten by this! :)
> 
> --David
> 
> (BTW, while I am fairly certain of the above, there is -- as always -- a
> possibility I am sitting out in the middle of nowhere babbling
> incoherantly.  If this is the case, please someone slap me and correct the
> above)
> 
> On Tue, Dec 18, 2001 at 04:59:03PM -0500, Hugh Brown wrote:
> > I am having some troubles with MX records for a web server.
> > 
> > I have a host named web.host.dom and a host named mail.host.dom
> > 
> > In dns I have the following
> > 
> > 
> > host.dom.      IN      SOA     ns.host.dom.     hostmaster.ns.host.dom.
> > (
> >                         2001090912 ; serial
> >                         3600 ; refresh after 1 hour
> >                         900 ; retry after 15 minutes
> >                         604800 ; expire after 1 week
> >                         1800 ; default_ttl is 1 hour
> >                         )
> > 
> > web                     IN      A       xxx.xxx.xxx.xxx
> >                         IN      MX 0    mail
> > 
> > 
> > 
> > mail                    IN      A       xxx.xxx.xxx.xxx
> >                         IN      MX 0    mail
> > 
> > 
> > I assumed this meant that if I sent an email to hugh at web.host.dom that
> > it should get sent to hugh at mail.host.dom
> > 
> > I tried it and got a bounced message back saying undeliverable.
> > 
> > Help.
> > 
> > Hugh
> > 
> > 
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-- 
------------------------------------
System Administrator/Unix Consultant
hugh at vecna.com
Vecna Technologies, Inc
6525 Belcrest Rd, Suite 612
Hyattsville MD, 20782
301.864.7253
http://www.vecna.com