For default Exchange 2010 use RPC dynamic ports from 1026 to 49000 on Mailbox rol
and RPC dynamic ports from 6005 to 49000 on Client Access rol.
If you are deploying CAS rol and MAILBOX between subnets and across firewall you can restrict RPC dynamic ports.
You can use command netsh for this task.
To show present configuration:
Netsh int ipv4 show dynamicportrange tcp
Netsh int ipv4 show dynamicportrange udp
To change configuration:
Netsh int ipv4 set dynamicportrange protocol=tcp startport=49152 numberofports=255
Netsh int ipv4 set dynamicportrange protocol=udp startport=49152 numberofports=255
Restart to apply changes.
Note: The minimum range of ports on W2008R2 that can be set is 255. The minimum starting port that can be set is 1025. The maximum end port (based on the range being configured) cannot exceed 65535.