As the level of replication activity increases or as server or network resources become constrained, there may be performance reasons to place the Publisher and Distributor on separate servers. This may be an appropriate configuration when high loads are present, such as when a busy online transaction processing (OLTP) server is configured as a Publisher. Using a separate Distributor reduces local processing and disk usage on the Publisher, although it increases overall network traffic somewhat.
Note Using a separate Distributor requires separate Microsoft® SQL Server™ installations (two licenses), one for the Publisher and one for the Distributor.
This scenario is similar to the central Publisher scenario, except that separate computers perform the publishing and distribution tasks. This is useful when the Publisher (for example, a heavily used OLTP server) should be freed from the distribution tasks because of performance and storage space considerations. The Publisher must be connected to the Distributor by a reliable, high-speed communications link.