Applies to:
Windows 10/ 2016
Windows 8.1/ 2012 R2
Windows 8 / 2012
Windows 7 SP1/ 2008 R2
Background:
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Normally the common thing for IT administrators to do is to disable ipv6 in the network adapter.
Control PanelNetwork and InternetNetwork Connections
Right-click on a network adapter
Click on “Properties”
Uncheck the box for "Internet Protocol Version 6 (TCP/IPv6)"
Warning: This is unsupported by us (Microsoft)
The supported work-around that many IT administrators end-up using is described in:
929852 How to disable IPv6 or its components in Windows
Investigation:
===========
A network trace (Message Analyzer/Wireshark) showed that the device with the MAC address, [00-1A-1E-01-43-65], was sending Router Advertisement in the network segment.
Windows Vista and Windows Server 2008 and newer OS’es implements RFC 3484 and uses a prefix table to determine which address to use when multiple addresses are available for a name.
By default, it favors IPv6 global unicast addresses over IPv4 addresses.
969029 The functionality for source IP address selection in Windows Server 2008 and in Windows Vista differs from the corresponding functionality in earlier versions of Windows
https://support.microsoft.com/?id=969029
For information about RFC 3484:
Default Address Selection for Internet Protocol version 6 (IPv6)
http://tools.ietf.org/html/rfc3484
RFC 4291 will let you set ipv4 precedence over ipv6
Using SIO_ADDRESS_LIST_SORT
https://msdn.microsoft.com/en-us/library/windows/desktop/ms740614(v=vs.85).aspx
For information about RFC 4291:
IP Version 6 Addressing Architecture
http://tools.ietf.org/html/rfc4291
Start, CMD (Run As Admin)
netsh interface ipv6 show prefixpolicies
Note that higher precedence in prefix policies is represented by a lager "precedence" value, exactly opposite to routing table "cost" value.
40 1 ::/0
30 2 2002::/16
20 3 ::/96
10 4 ::ffff:0:0/96
Note that IPv6 addresses (::/0) are preferred over IPv4 addresses (::/96, ::ffff:0:0/96).
We can create a policy that will make Contoso IPv6 tunnel less favorable than any IPv4 address:
netsh interface ipv6 add prefixpolicy 2001:470::/32 3 6
2001:470::/32 is Contoso's prefix, 3 is a Precedence (very low) and 6 is a Label.
Recommendation:
================
Use the “Prefer Ipv4 over IPv6” using the custom .admx here:
How to Disable IPv6 through Group Policy
OR use GPP to set the Disabled Components for “Prefer IPv4 over IPv6”
929852 How to disable IPv6 or its components in Windows
https://support.microsoft.com/?id=929852
OR if in individual machines:
Instead of manually configuring these settings, there is a fix it:
2533454 Resolving Internet connectivity issues after World IPv6 Launch (June 6, 2012)
https://support.microsoft.com/?id=2533454
Yong “Hailing from Long Beach, CA. today”.