I described the LAN AutoDisconnect value name in tip 0019.
When AutoDisconnect is present in the registry, two additional Value Names can be added, both are REG_DWORD data types:
Announce is the network announce rate, in seconds, that determines how often the server is announced to other computers on the network. The default is 240 seconds.
anndelta is the number of milliseconds the Announce rate can vary, allowing a degree of randomness. The default is 3000 milliseconds.