Changing ISP: what changes should I make on the DNS of mail server?

Assuming that you own the zones (forward and reverse) and control the name servers for the zone, and manage the mail exchangers for the zone, this is a fairly simple (though somewhat time consuming) task.

1. Obtain new IPs for all affected hosts (mail servers, spam and anti-virus appliances, etc..)

2. Create the new Reverse (ip to name) zone file.

3. At least a week before the cutover, you should lower the TTL for the zone files to a short interval, like 1 hour. This will greatly increase the traffic to your name server, but it will minimize the impact caused by incorrect/old/stale records being in other people's caches.

4. At the time of the cutover, make a backup of the original Forward (name to IP) zone file and make you changes. Be sure to increment the serial number.

5a. Tell your name server software (you are using BIND 9, right?) to reload the affected zone files.

5b. Change the IP addresses on the afflicted servers.

6. A few days after the cutover, when everything should be working fine, raise the TTL for the zone files back up to something more reasonable, like once a day or once a week.

NOTE: this process is complicated somewhat if you are also re-IP'ing the name servers for the zones.

fpsm

fpsm at 2007-7-6 22:28:18 >