Moving MX record

Posted on 2007-03-19
Last Modified: 2008-02-07
I have an exchange server 2003 that currently shares a public IP with a web server  Our firewall uses port forwarding for OWA.  All http and https are forwarded to the web server, and all 8650 is forwarded to our exchange server for OWA.  

What I want to do:  I want to move the exchange server to a different public IP, without causing any interuption to email delivery (or website).  I was thinking that I would create a second MX record (20) to point to the .201 public address, which would mean I would add an additional NIC on my Exchange and do a 1to1 NAT to the .201 address.  I would wait for a week for the second MX record to replicate on the internet and then delete the first MX record that points to the .200 IP.

Is this the proper way to do this.

Question by:ptran2000
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LVL 26

Expert Comment

ID: 18751168
You can do all of that and skip adding the second nic.

If you add a second MX record (with a higher number) you can leave the server on the original IP without losing any mail because all mail servers will try the lower number MX first. Once you've waited long enough for the record to propagate, change the IP of the server .201 and remove the original MX record. Anyone who sends mail to you before the original MX is fully gone will try the original IP, fail (since you changed it) and should then proceed to the new IP. I did this and didn't lose any email.  
LVL 16

Expert Comment

ID: 18751430
I agree with jar3817 that you can leave the second nic off. You don't need it. You should set your DNS up with a higher number for the new IP address. Thats also correct.

But...if I understand you correctly you don't have to change the IP address of the Exchange server. You use port forwarding on the firewall so you just have to configure the firewall to use the new external IP. If you have a more sophisticated firewall you can also set up more than one external IP. That means you could configure port forwarding for the new IP on port 25 for mail delivery and ports 80 and 443 for OWA simultaneously with the existing port forwarding. After a while just delete the old DNS record and all should be well.

Author Comment

ID: 18757942
this is what I have right now
A records

MX records

if I add another MX record (20)

or should it be
Would I need to create an A record for also?


LVL 26

Accepted Solution

jar3817 earned 250 total points
ID: 18758061
The two MX records need to be different (like mail and

Yes you need to create an A record for the new MX (mail2) and set it to the new IP the machine is moving to.

Author Comment

ID: 18758619

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