You need to ensure that domain controllers only replicate between domain controllers in adjacent sites.
What should you configure from Active Directory Sites and Services?

A.
From the IP properties, select Ignore all schedules.

B.
From the IP properties, select Disable site link bridging.

C.
From the NTDS Settings object, manually configurethe Active Directory Domain Services connection
objects.

D.
From the properties of the NTDS Site Settings object, configure the Inter-Site Topology Generator for each
site.

Explanation:
http://www.omnisecu.com/windows-2003/active-directory/what-is-site-link-bridge.htm
What is Site Link Bridge and How to create Site Link Bridge
A site link bridge connects two or more site links.A site link bridge enables transitivity between site links. Each
site link in a bridge must have a site in common with another site link in the bridge.
By default, all site links are transitive and it isrecommended to keep transitivity enabled by not changing the
default value of “Bridge all site links” (enabled by default).

We may need to disable “Bridge all site links” and create a site link bridge design if
• When the IP network is not fully routed.
• When we need to control the replication flow in Active Directory.