Internal DNS IP resolutino Question

[Kathleen]

Ok.....hopefully I will ask this right.

We moved our email inside our firewall. Everything seems ok except the fact that our client machines point to the old external email address and now they can't get to the internal address without changing their email settings. Is there a way to get the internal DNS to point the old server IP to the new IP so that the users don't have to change anything. If the client points to 123.123.123.123....but now the machine is actually 12.1.1.3 can we get the dns to do sometype of forwarding???

[Steven E. Protter]

You need to change the record on the internal DNS server to point to the new IP address.

Lets say the mail server's name is called mail.your.net

It used to resolve to 123.123.123.123

nslookup mail.your.net reuturns:
123.123.123.123

Change the DNS record to reflect the new addresss:

12.1.1.3

If the clients had the old IP address hardcoded into their setup, say they are using the DS directive in their sendmail file, then they will all have to be reconfigured.

In HP-UX

vi /etc/mail/sendmail.cf

DS
12.1.1.3


save it

/sbin/init.d/sendmail stop
/sbin/init.d/sendmail start


This should be totally feasible to be done with a simple DNS record change on your internal DNS server.

If you have the same network name on both sides of the firewall, say your.net, you can set up forwarding.

For this situation though, you probably don't want to do it, just change the one DNS record to reflect the change.

What you have not specified is the OS of the clients and the DNS server. That would help for more specific assistance.

SEP

[Kathleen]

We are using HP-UX 11.0 with HP Openmail 7.0. The windows clients all point to the old external IP. We changed our indns to the new ip and that is all wonderful. The problem is the clients. We don't want to touch all of them to get them working with this new IP. We were hoping there could be some seamless translation of the client looking for the old ip, and being redirected to the new IP.

[Brian DelPizzo · Accepted solution]

With hardcoded IPs, you are out of luck when dealing with DNS. You are going to have to modify each client and hopefully use the DNS name not a hard IP.

Your only other option would be to keep a server at the old IP and have it forward mail for you. MAYBE.