For IP-based and SMTP-based Active Directory site links, an option exists to disable the Bridge all site links option. This option is enabled, by default, and defines the site links as transitive. This transitivity means that domain controllers, member servers, and devices may traverse site links to get from site A to site C, through site B, even though site A and site C are only connected with site links to site B and not with each other.
In complex networking environments, more granular control over replication and service discovery might be needed. In these scenarios, disabling site-link transitivity and manually defining site-link bridges might be the preferred method.
