I have 3 sites that in my 2008 R2 AD, each site with 2 domain controllers.
We are running into a problem when something is modified on the user account such as a group addition, change password or even an account creation and it takes roughly 15-20 minutes before that password or group change is replicated to the domain controllers and other sites.
I have modified the Inter-Site Transport to 15 minutes, which is the lowest it can go. However, this presents a problem as users to not have 15 minutes to wait before they can gain access to the system.
Is there any other ways to speed up the AD replication time?