How Autodisconnect Works in Windows NT and Windows 2000


This article documents the Windows NT and Windows 2000 local area network (LAN)-related Autodisconnect parameter.

Windows NT and Windows 2000 use two different Autodisconnect parameters; one for disconnecting Remote Access Service (RAS) connections and another for disconnecting LAN connections. The RAS Autodisconnect parameter is documented in the Microsoft Knowledge Base article Q153944, but the LAN version is undocumented. The only published reference to this Autodisconnect is in the Windows NT Resource Kit NT Registry Entries help file, in an overview of entries for the LanmanServer Parameters section.

More Information

You can find the LAN Autodisconnect parameter in the registry under the subtree HKEY_LOCAL_MACHINE under the subkey:

NOTE: The preceding entry must be located on the computer that has the share or shares.

The purpose is to disconnect idle sessions after a set number of minutes. The number of minutes can be set at a command prompt using the net config server command.

For example, to set the Autodisconnect value to 30 minutes, you would run the following command line:

net config server /autodisconnect:30
The valid value range is -1 to 65535 minutes at the command line. To disable Autodisconnect set it to -1.

Setting Autodisconnect to 0 does not turn it off and results in very fast disconnects, within a few seconds of idle time. (However, the RAS Autodisconnect parameter is turned off if you set it to a value of 0.)


  • It is preferable to modify the LAN Autodisconnect directly in the registry. If you modify it at the command line, Windows NT and Windows 2000 may turn off its autotuning functions. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

    128167 Server Service Configuration and Tuning
    The valid value range if you edit the LAN Autodisconnect parameter in the registry is 0 to 4294967295 (Oxffffffff).
  • For a Windows 2000 Server in a Domain, running either as a domain controller or as a server, the maximum value is 65,535 (0xffff). Values set above this will be returned to 0xffff after policy refresh. Windows 2000 Servers in a workgroup may be set to any value as indicated.

    If you configure the Autodisconnect option to -1 at the command prompt, Autodisconnect is set to the upper value in the registry. This is approximately 8,171 years (not tested), which should be long enough to be the equivalent of turning Autodisconnect off.
  • The registry does not allow you to add a -1 value. However, that modification may be made at the command prompt with the following command:

    net config server /autodisconnect:-1
    When this is set, two additional registry keys are added:

    anndelta: REG_DWORD: 0xbb8
    announce: REG_DWORD: 0xf0
    Announce: Specifies the network announce rate, in seconds. This rate determines how often the server is announced to other computers on the network.

    Anndelta: Specifies the delta value for the announce rate, in milliseconds. This value specifies how much the announce rate can vary from the period of time specified in the announce member.

    The delta value allows randomly varied announce rates. For example, if the announce member has the value 10 and the anndelta member has the value 1, the announce rate can vary from 9.999 seconds to 10.001 seconds.
  • After a few minutes of idle time, your mapped drive or drives may be disconnected, and a red "X" may appear next to the mapped drives in Windows Explorer.For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

    305355 Some Compaq Programs Cause Mapped Drives to Be Disconnected

Article ID: 138365 - Last Review: Feb 19, 2007 - Revision: 1