A client connected to an Ethernet switch may receive several logon-related error messages during startup

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This article was previously published under Q202840

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SYMPTOMS

On a client computer that is connected to an Ethernet switch, you may receive several logon-related error messages during Startup.

In the event log, you may receive the following error message:

5719 - No domain controller available

NOTE: The source of this error may be the NetLogon service and how the NetLogon service sets up its secure channel.

Also, if you log on to the console before Startup has completed, you may receive one of the following error messages:

No domain controller was available to validate your logon.
A domain controller for your domain could not be contacted. You have been logged on using cached account information. Changes to your profile since you last logged on may not be available.

You may receive this error message only when you make the initial attempt to log on to the computer. When you make subsequent attempts to log on to the computer, you may not receive this error message.

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CAUSE

This behavior can occur because some Ethernet switches have a feature that checks the ports for a loop condition when the ports become active (the Learning mode for the Spanning Tree Algorithm feature). If a loop is found, all traffic is blocked from accessing the port. This process of checking for a loop condition takes approximately 10 to 15 seconds during which the Windows NT Workstation-based computer seems to be on the network, yet no traffic is being passed. The NetLogon service packets (along with any other traffic during that time) are lost.

If you have a hub at the end of the port, the hub has already brought the port up. Your connection is only unsuccessful when your computer is connected directly to the switch.

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RESOLUTION

To resolve this behavior, disable the Spanning Tree Algorithm feature of your Ethernet switch.

For information about how to disable the Spanning Tree Algorithm feature on a switch, contact the switch manufacturer.

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WORKAROUND

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows

To work around this behavior, on the clients add the following parameter to the registry:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Netlogon\Parameters

Value Name: ExpectedDialupDelay
Data Type: Reg_Dword
Data Value is in seconds (default = 0)
Data Range is between 0 and 600 seconds (10 minutes)

This workaround forces the NetLogon service to pause for the specified amount of time before the service attempts to establish its secure channel.

NOTE: Unless you reconfigure your switch, you may still experience the symptoms described in the following Microsoft Knowledge Base article:

168455 (http://support.microsoft.com/kb/168455/ ) DHCP renewal failures on switched networks

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