How can an administrator trigger replication to an RODC?

You can use the following methods:

1.    By running the repadmin /replicate or repadmin /syncall operations.

2.    By using the Active Directory Sites and Services snap-in. In this case, you can right-click the connection object and click Replicate Now.

3.    You can use Active Directory Sites and Services on a writable domain controller to create an inbound replication connection object on any domain controller, including an RODC, even if no inbound connection exists on the domain controller.This is similar to running a repadmin /add operation.