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Win7 seems to prefer IPv4 native to IPv6/6to4 - which is not what the policy table says - which is right?

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I have a Win7 machine. It has an IPv4 address, and an IPv6 address via 6to4 (from upstream - the PC is not the 6to4 site router). I believe that IPv6 should preferred to www.ietf.org, which has both IPv4 and IPv6 records in the DNS. It is not, however. Both "ping www.ietf.org" and using a web-browser to that same name use IPv4. I can see the DNS queries go out and an A and AAAA record returned.
My prefix policy table shows IPv6 should be preferred. Unless I don't know how to read it, 6to4 is clearly precedence 40, and native IPv4 is precedence 10. Be clear I am not using IPv6/Teredo - I expect IPv4 to be preferred to that. But I expect 6to4 to be preferred to IPv4.
What is going on?
My prefix table:
C:\Windows\system32>netsh int ipv6 sho prefix
Querying active state...Precedence Label Prefix
---------- ----- --------------------------------
50 0 ::1/128
40 1 ::/0
30 2 2002::/16
20 3 ::/96
10 4 ::ffff:0:0/96
5 5 2001::/32
Question
Answers
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Precedence Label Prefix
------------- ------ --------------------------------
50 0 ::1/128 = localhost
40 1 ::/0 = default (IPv6 native)
30 2 2002::/16 = 6to4 (IPv6)
20 3 ::/96 = IPv4 compatibility
10 4 ::ffff:0:0/96 = IPv4 compatibility
5 5 2001::/32 = Teredo (IPv6)
http://www.dd-wrt.com/wiki/index.php/IPv6_%28tutorial%29#6to4_IPv6_as_default_protocol
Quote:
6to4 IPv6 as default protocol
As per RFC3484 §2.1 default policy table, having a 6to4 enabled LAN will mean that 6to4 IPv6 will only be used to communicate to a server if the server is having a 6to4 adress too (ie: 2002: prefix on its address) or if there is no IPv4 address assigned to the server name (ie: no A but an AAAA).In short the following makes IPv6 (6to4) default on IPv6 enabled Windows boxes:
1. Start -> Run -> "cmd" -> "netsh" -> "interface" -> "ipv6"2. To set IPv6 (6to4) as the default protocol on Microsoft Windows...
set prefix ::1/128 50 0 set prefix ::/0 40 1 set prefix 2002::/16 30 1 set prefix ::/96 20 3 set prefix ::ffff:0/96 10 4 set prefix 2001::/32 5 5
Only the 2002::/16 line (6to4 prefix policy) is changed.
3. To make things goes back to original mode (IPv4 preference)...
set prefix ::1/128 50 0 set prefix ::/0 40 1 set prefix 2002::/16 30 2 set prefix ::/96 20 3 set prefix ::ffff:0/96 10 4 set prefix 2001::/32 5 5
And Voilà ;-)Shorter method also available here:- Proposed as answer by ThreeDots Saturday, November 21, 2009 4:26 AM
- Marked as answer by Nicholas LiModerator Tuesday, November 24, 2009 9:34 AM
All replies
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Precedence Label Prefix
------------- ------ --------------------------------
50 0 ::1/128 = localhost
40 1 ::/0 = default (IPv6 native)
30 2 2002::/16 = 6to4 (IPv6)
20 3 ::/96 = IPv4 compatibility
10 4 ::ffff:0:0/96 = IPv4 compatibility
5 5 2001::/32 = Teredo (IPv6)
http://www.dd-wrt.com/wiki/index.php/IPv6_%28tutorial%29#6to4_IPv6_as_default_protocol
Quote:
6to4 IPv6 as default protocol
As per RFC3484 §2.1 default policy table, having a 6to4 enabled LAN will mean that 6to4 IPv6 will only be used to communicate to a server if the server is having a 6to4 adress too (ie: 2002: prefix on its address) or if there is no IPv4 address assigned to the server name (ie: no A but an AAAA).In short the following makes IPv6 (6to4) default on IPv6 enabled Windows boxes:
1. Start -> Run -> "cmd" -> "netsh" -> "interface" -> "ipv6"2. To set IPv6 (6to4) as the default protocol on Microsoft Windows...
set prefix ::1/128 50 0 set prefix ::/0 40 1 set prefix 2002::/16 30 1 set prefix ::/96 20 3 set prefix ::ffff:0/96 10 4 set prefix 2001::/32 5 5
Only the 2002::/16 line (6to4 prefix policy) is changed.
3. To make things goes back to original mode (IPv4 preference)...
set prefix ::1/128 50 0 set prefix ::/0 40 1 set prefix 2002::/16 30 2 set prefix ::/96 20 3 set prefix ::ffff:0/96 10 4 set prefix 2001::/32 5 5
And Voilà ;-)Shorter method also available here:- Proposed as answer by ThreeDots Saturday, November 21, 2009 4:26 AM
- Marked as answer by Nicholas LiModerator Tuesday, November 24, 2009 9:34 AM
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