Hello
We have a domain with 12 DCs and 10 Sites. all servers are windows 2008 R2. we use Hub and spoke topology for our sites, that 2 sites with 2 DCs in each are the Hubs and other 8 DCs are the spokes in other sites. most of the clients in each site are windows XP SP3 and are update. replication between sites is working well.
The problem is that clients in two sites(4 and 5) using others DCs randomly, for authentication, instead of their local DC.
I have also checked DNS for SRV records in site directory and other places for the problem but still there is no luck to solve the problem.