RODC replication – some thoughts

Are changes instantly replicated from a domain controller ?

 Depends on the replication schedule set between sites. Generally, no.The time it takes to replicate changes to an RODC depends on where the changes have been made and how fast they get replicated to the RODC. Changes made on a distant site can take more time to replicate to the RODC than changes made in the same site/the site next to the RODC.

 Can the replication time be changed ?

AD Sites and Services will allow you to configure your replication topology, frequency and any other scheduling. The topology for AD Sites and Services is more or less the same as in Windows 2003

I order to reduce the amount bandwitdth used then the replication traffic should be configured to only allow inbound replication, no local changes, and therefore no outbound replication. RODCs can replicate from writeable DCs.

The most important aspect is replication of password changes. That is covered by this article:  

http://technet.microsoft.com/en-us/library/cc730883.aspx    

What operations fail if the WAN is offline, but the RODC is online in the branch office?

If the RODC cannot connect to a writable domain controller running Windows Server 2008 in the hub, the following branch office operations fail

• Password changes

• Attempts to join a computer to a domain

• Computer rename

• Authentication attempts for accounts whose credentials are not cached on the RODC

• Group Policy updates that an administrator might attempt by running the gpupdate /force command
  

  What operations succeed if the WAN is offline, but the RODC is online in the branch office?

  If the RODC cannot connect to a writable domain controller running Windows Server 2008 in the hub, the following branch office operations succeed:

• Authentication and logon attempts, if the credentials for the resource and the requestor are already cached.

•  Local RODC server administration performed by a delegated RODC server administrator.