We're getting ready to consolidate our Exchange Server organization to a new data center. We're physically moving all our servers and assigning them new IP addresses. Are there any special concerns associated with changing the IP address of a working Exchange server?
Probably not. Exchange heavily uses DNS for service location and message delivery, so as long as you've updated the DNS records (along with any HOSTS file entries that you might have used to eliminate the need for WINS) for the servers you're moving, you should be fine. By default, all the virtual servers should use the All unassigned setting, which means that they'll automatically pick up the new addresses. If you've assigned specific IP addresses to any of your virtual servers, you'll need to update those addresses, too.
If you're using clustering, the answer is slightly different. In a cluster, you must update three items: the cluster's IP address resources, the IP addresses assigned to the virtual servers, and the IP addresses assigned to the physical cluster nodes.
One last thing: Before you change the IP address, you might want to make sure you know the Administrator password for each machine. After you move the servers to their new network segment, they might not be able to reach their original domain controller (DC) to let you log on; you might need to log on as a Local Admin to fix any last-minute problems.