JSI Tip 9268. Settings for minimizing periodic WAN traffic when you connect to a domain controller over a dial-on-demand link.

Microsoft Knowledge Base Article 819108 contains the following summary:

This article describes the registry settings and the Group Policy settings that affect periodic wide area network (WAN) traffic and Integrated Services Digital Network (ISDN) costs. If you have a dial-on-demand link, it might be unexpectedly enabled by periodic WAN traffic. You can configure the system's components and services to minimize periodic WAN traffic and to reduce ISDN costs.