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Re: Virtual DNS questiona and reverse lookup table conflicts



Daniel B. Thurman wrote:
Christopher K. Johnson wrote:
Bruno Wolff III wrote:
On Sat, Dec 06, 2008 at 13:34:06 -0800,
  "Daniel B. Thurman" <dant cdkkt com> wrote:
Is it possible to have a single DNS server support
two different domain names, with each domain
name having it's own forward and reverse lookups?

It is possible for PTR lookups to return different results based on the
IP address that the request comes from. I don't use bind and so can't
give you advice on how to set this up (assuming that it will solve your
problem), but googling for "split horizon" and "bind" should find help
in doing that.
Check out "bind views".

Thanks for the tips.

But the more I think about it, how does bind know which
reverse ip domain name to return?  Domain1 or Domain2?

I am missing the logic behind this.

It matter which domain name is returned because nowadays, there
are email sites that do a reverse ip lookup to ensure that the domain
name matches with the ip address and if they don't match - the email
message is rejected, for example.

As far as I know you can have only one reverse map for one ip-address. But for the e-mail server it should be enough for you to have one valid forvard reverse pair.

If you have two domains domain1 and domain2 you would just make the domain2 use mail.domain1 as it's mail server. If mail server checks if the mail server is in same domain with mail address it's too braindead to be used as there is too many domains which use mail servers belonging to other domain.

So in domain1.com bind config you would have

        IN MX 1 mail.domain1.com.
mail   IN A 10.0.0.1

In reverse you will have

1 IN PTR mail.domain1.com.

And in domain2.com forward you would put.

IN MX 1 mail.domain1.com.

-VPK


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