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Problem with local DNS domaine name

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by pcole11 1 view

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I recently upgraded my Windows NT4 domain to active directory. Following the upgrade documentation from MS, I appended the local town name to the domain because our organization has offices in two different towns. So the domain name went from "Smith" to boston.smith.org. The upgrade went fine, and I now have primary and secondary AD and DNS servers working and replicating without error.

The problem is, we host our own email, and we can get to it outside of the network by going to mail.smith.org, but we cannot get to this from within our network. I know that I need to add a host record to DNS to accomplish this, but when I try to add the record for "mail", it automatically appends the .boston.org part which will not work. How can I override the automatic appendage and enter a Host record for "mail" with only smith.org?

11 replies

by dumphrey

because the isp dns does not care how many internal domains you have, just what IP address to forward the mail to. As long as your firewall is forwarding mail for mail.smith.org to the correct ip address, it should be fine. You can set it up so that every email address is just smith.org, not boston.smith.org etc. This will simplify addressing and mail set up.
If I am on the wrong track I apologize, my head is killing me atm...
Post back with some more info on your set up, no need for real ip addresses, just the topology.

by pcole11

I don't think the firewall comes into play because mail.smith.org works fine from outside the firewall. I think the problem is that when I use this url inside the firewall, the dns thinks it's local, so it never forwards the request out to the isp, and it has no local record to resolve the query. I had the same problem at the other branch, only there it wasn't an upgrade, it was a new installation. They have their own domain name, and I did not use the town name. So they are just mail.jones.org, but this would not work inside the firewall until I added a host record for "mail" and pointed to the mail server. I think it's the same issue at smith.org, but I can't seem to add any host records that do not include boston.smith.org. When you add a local host record, it automatically appends the domain name, and I can't find a way to override that.

by dumphrey

When you add a new dns record by hand, it appends the domain name unless you add it in yourself. So in creating a new mx record, do not enter just mail as the host name on the record, but mail.smith.org. This will create a sub folder in your dns tree with the new domain listed.
So if your domain was bob.com, and you entered a host as mail.sue.com, it would be in a folder labeled sue, and its dns would be mail.sue.com.bob.com (if I remember correctly).
But as I said, the whole key is adding the domain name to the host name at the time of the record creation.

by dumphrey

in the LAN DNS, what is its fqdn? According to your set up, it should be mail.boston.smith.org. Is there any particular reason that fqdn does not work or that you can not use it?

by cg it

In a Windows domain using Exchange Server, and SMTP, Exchange uses the AD domain name to process mail. so if your domain is .com and your users are @domain.com and your MX record reflect the .com = 10.com mail will be delivered.

if you want Exchange to host other domain names, then you have to add those domain names in Exchange, as well as having your DNS server resolve the name.

what configuration you outlined sounds a lot like child domains where you have [user]@mrsmith.domain.com and [user]@ mrssmith.domain.com and you want mail addresses to both domains to go to the same user.

by dumphrey

ignores extended dns. It only resolves host names, and assumes everything is in the same dns name space. So use of dns aliass in a multi domain single server set up becomes needed.

by pcole11

I guess I could have staff use the fqdn. That would work, but would confuse my very non-technical (social services) staff.
I should have mentioned that we are not running Exchange, we are running Lotus Domino and staff use the Notes client for email, so no internal mx record is being used. The only time we would want to use the web mail interface from inside the firewall is when training staff on how to access email from home. It would be very confusing to train them to use mail.boston.smith.org in training, but to use mail.smith.org at home. This will become a bigger issue next year, as we would like to do away with the Notes client and use the browser as the email client in Notes 8. I think there must be another type of record (alias?) that will allow me to do this, I was just hoping for a quick fix, but I think I may have to resort to reading TFM :)
Thanks for your time.

by dumphrey

It should work just fine. Open your DNS console, right click on your zone, and choose new alias. In the top box enter mail.smith.org, in the lower box browse to mail .boston.smith.org. Then if you do an NSlookup on mail.smith.org, you should get the LAN address of mail.boston.smith.org.

Its simple to do, but you should document what and why you did it, for anyone else that may come after you, or for yourself down the road.

by pcole11

The alias had the same issue, appending the full fqdn at the end.
The resolution was to create a new forward lookup zone, "smith.org" and then create the mail host record under that.
Thanks for your help.

by dumphrey

Makes sense as well, you do need a dns zone for the domain...

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