What is the Management Tier?
The management tier provides domain services, management, and monitoring capabilities, and an interface for analyzing site activity. You can consider the servers in this tier to be in the design-time environment because they provide services and functionality that are transparent to clients—clients do not access the services in this tier directly. The servers in this tier manage and support the servers that clients access directly.
Besides providing authentication services, the servers in this tier enable administrators to monitor the performance of each server from a central location, and enable business users to analyze site productivity and update specific areas of a site without affecting the run-time operations (service to clients).