virtual domains and zone files
Andrew
andrew at arda.homeunix.net
Tue Dec 2 04:09:48 UTC 2003
Well, I did open a can of worms, didn't I? 'Virtual domain' is such a
common term when referring to email delivery I didn't think twice about
using it here. If there is a more acceptable term to DNS admins, I'd
like to know what it is because, right now, I have no other way to label
what I'm talking about.
The zone file I posted really is for the arda.homelinux.net zone,
honest. It's purpose in life is to tell hosts on my network that if
someone sends mail to user at arda.homelinux.net, use
callisto.arda.homeunix.net as the mail exchanger. There are no A records
in this zone file because there are no hosts with the FQDN of
<hostname>.arda.homelinux.net on my network. The A records for io,
europa, and callisto reside in the arda.homeunix.net zone file. Which is
what you might expect given that their FQDNs all end in arda.homeunix.net.
All I wanted to know is whether the SOA and NS records in the
arda.homelinux.net zone file are really necessary. Having thought about
how hosts determine where to send mail addressed to 'virtual' domains, I
think that they are. Of course, the whole purpose of posting my question
was to allow people more knowledgeable than I to confirm or deny my
suspicion.
So I suppose I've answered my own question. I'm surprised at how much
consternation my question has caused, though, given the wide use of
'virtual' domains in email delivery and the fact (as far as I know) that
DNS must be set up specifically to allow such delivery.
For those who are interested, all my zone files and my named.conf file
are posted on my web site. Go to:
http://www.arda.homeunix.net/dnssetup.shtml
Andrew
Andrew wrote:
> My mail server hosts a virtual domain that does not include any hosts in
> it. Here is the zone file I use with this domain.
>
> # cat /etc/namedb/master/arda.homelinux.net.zone
> $ORIGIN .
> $TTL 10800 ; 3 hours
> arda.homelinux.net IN SOA europa.arda.homeunix.net.
> postmaster.arda.homeunix.net. (
> 20030416 ; serial
> 10800 ; refresh (3 hours)
> 3600 ; retry (1 hour)
> 604800 ; expire (1 week)
> 3600 ; minimum (1 hour)
> )
> NS io.arda.homeunix.net.
> NS europa.arda.homeunix.net.
> MX 10 callisto.arda.homeunix.net.
>
> As things stand now, I can deliver mail to user at arda.homelinux.net but I
> would like to know if this zone file looks reasonable or if there are
> elements that don't need to be there.
>
> Andrew
>
>
>
>
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