If you have large Exchange organization with multiple servers and roles, you need to be careful about update. I’ve recently updated our Exchange Servers to Update Rollup 6. I want to share my experiences with update process.

First of all, you need to update roles with this order:

1. Client Access Servers
2. Hub Transport Servers
3. Mailbox Servers (DAG)

Client Access Servers:
If you have CAS Array, you don’t need to do any extra process, you can just install updates. After installation, reboot is not required but i rebooted all CAS servers to see what happens after reboot. It’s good to check services after reboot. If they are all started, then it’s successful.