Teredo only used as last resort after IPv4 (Was: ipv6-ops Digest, Vol 25, Issue 9)

Jeroen Massar jeroen at unfix.org
Thu Apr 12 15:44:36 CEST 2007

[reminds himself that this is an operational list, reply-to set to
users at ipv6.org which is more appropriate for end user questions's]

nenad pudar wrote:
> I have vista now (torredo enabled by default) ,have patched lynksys
> software with Earthlink patch ,it is working fine except that I cannot
> browse since DNS is not working (reverse DNS seems to be OK)
> C:\Users\Shone>tracert 2001:5a0:d00::5
> Tracing route to gin-nto-core2.ipv6.teleglobe.net
> <http://gin-nto-core2.ipv6.teleglobe.net> [2001:5a0:d00::5]
> over a maximum of 30 hops:
>   1  2282 ms    38 ms    41 ms  iad0-stf.hotnic.net
> <http://iad0-stf.hotnic.net> [2001:4810:0:100::3]

stf aka "Six To Four" aka 6to4, aka 2002::/16

Clearly you are not using an Earthlink tunnel, which would go over their
network, and most likely not Teredo either, though it might be that
hotnic also runs a Teredo relay on their box, don't know if they do
that, it just might. Most likely you are using 6to4 though.

When Vista notices it can use 6to4 it uses that.

You might want to check with "netsh int ipv6 show address" what options
you have available. Or check http://www.sixxs.net/tools/ipv6calc/ which
will display the details for you. (www.ipv6.sixxs.net also works of course)

> C:\Users\Shone>tracert www.ipv6.sixxs.net <http://www.ipv6.sixxs.net>
> Unable to resolve target system name www.ipv6.sixxs.net
> <http://www.ipv6.sixxs.net>.
> Am I missing something here ?

Yes cut and pasting correctly ;) You might want to try only
"www.ipv6.sixxs.net" without the quotes. See below for an example.

> Is Vista using IPV6 for DNS transport trying to communicate with DNS
> server ?

Yes, but it has the option to fall back to IPv4 transport. Pure native
IPv6 DNS is mostly impossible anyway as one need to be able to reach the
IPv4-only rootservers. Of course having a IPv6 DNS caching resolver that
can speak both IPv4/IPv6 alleviates that problem.


Using my sweet AYIYA tunnel:

C:\Documents and Settings\jeroen>tracert www.sixxs.net

Tracing route to noc.sixxs.net [2001:838:1:1:210:dcff:fe20:7c7c]
over a maximum of 30 hops:

  1    27 ms    29 ms    29 ms  gw-159.dub-01.ie.sixxs.net

  2    28 ms    29 ms    26 ms  blanch-sr1-vlan8.services.hea.net
  3    28 ms    29 ms    29 ms  po1-ar1-cwt.hea.net [2001:770:8:31::1]
  4    28 ms    30 ms    28 ms  gige4-3-cr1-cwt.hea.net [2001:770:400:f::1]
  5    30 ms    29 ms    29 ms  gige3-2-cr1-kp.hea.net [2001:770:400:11::2]
  6    30 ms    29 ms    30 ms  gx-link.core.hea.net [2001:770:90:7::2]
  7    48 ms    49 ms    49 ms  eth10-0-0.xr1.ams1.gblx.net
  8    49 ms    47 ms    50 ms  ams-ix.ipv6.concepts.nl
  9    52 ms   117 ms    50 ms  2001:838:0:10::2
 10    49 ms    54 ms    51 ms  noc.sixxs.net

Trace complete.

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