Run DFSUTIL /PKTINFO and note that the client intermittently connects to out-of-site link targets / folder targets
Here is an example of what the incorrect order looks like in dfsutil /pktinfo gathered from the client computer. The client should have gone to ContosoFS1 when connecting to \\Contoso\DFSRoot\TargetFolder but the client was instead going to ContosoFS4 across the WAN.
Microsoft(R) Windows(TM) Dfs Utility Version 4.2 Copyright (C) Microsoft Corporation 1991-2005. All Rights Reserved.
Entry: \Contoso\DFSRoot\TargetFolder ShortEntry: \Contoso\DFSRoot\TargetFolder Expires in 0 seconds UseCount: 0 Type:0x1 ( DFS ) 0:[\ContosoFS4\TargetFolder] State:0x131 ( ACTIVE TARGETSET ) <- out of site IPv4-only Windows Server 2003 target client connected to 1:[\ContosoFS3\TargetFolder] State:0x21 ( ) <- out of site IPv4-only Windows Server 2003 target 2:[\ContosoFS5\TargetFolder] State:0x21 ( ) <- out of site IPv4-only Windows Server 2003 target 3:[\ContosoFS1\TargetFolder] State:0x121 ( ) <- In-site target should be at top of list but isn't because IPv6 incorrectly disabled
IPv6 protocol on the Windows Server 2008 target server has been unchecked on the network adapter properties but IPv6 has not been disabled using the DisabledComponents registry setting.
IPv6 on the Windows Server 2008 target server has a static address assigned but an IPv6 Subnet has not been defined and associated with the Target server's site in Active Directory Sites and services.
Preferred - Place a check mark next to "Internet Protocol Version 6 (TCP /IPv6)" on the IP Properties of the Adapter and reboot the server.
Place a check mark next to "Internet Protocol Version 6 (TCP /IPv6)" and configure a Static IPv6 addresses on the NIC properties and conifgure an IPv6 Subnet/Site association in Active Directory Sites and Services snap-in and reboot the server.
Unchecking IPv6 protocol on the adapter properties does not completely disable IPv6 and IPv6 cannot be removed from the operating system because the OS heavily relies upon IPv6 for internal processes. Unchecking the protocol will only result in transient network issues. The supported method to disable IPv6 [not recommended by the Microsoft Product Group] is to use DisabledComponents registry value as directed in KB929852.
NOTE: It is beyond the scope of this KB to determine which components of IPv6 should be disabled in a given environment using DisabledComponents.
929852 How to disable certain Internet Protocol version 6 (IPv6) components in Windows Vista, Windows 7 and Windows Server 2008
NLTEST.EXE and DFSUTIL.EXE are available as part of the XP and Windows Server 2003 Support Tools.