How is the "Replica Directory Node" supposed to function?

So I have a primary domain, that works.

Then during install of the second site I use the 5.0 ISO , I select " REPLICA DIRECTORY NODE", go through the setup and the Backup binds to the primary successfully

I see the link, between the two servers & if i go into teh APP center at either end i can see the sites for installation

so basically at the “remote site” :

  1. set the client DNS server to the REPLICA, so it can find the services

and if i issue a “DIG” against the DNS I see it is resolving correctly, to both the Primary site & the replica.

However if I try to BIND the client to the domain via the REPLICA site, it cannot work.

  1. Do i have to load any AD software onto the replica?
  2. Do I need to install “Active Directory Compatible Domain Controller” onto the “REPLICA DIRECTORY NODE”?

This would be to allow the clients can authenticate to this server , if the primary is off line
& the NAS can access the READ-ONLY LDAP records locally?