Berkely Netalyzr for IPv6/IPv4 testing (Was: Yahoo and IPv6)

Jeroen Massar jeroen at
Wed Jun 1 11:38:20 UTC 2011

On 2011-Jun-01 13:18, Tim Chown wrote:
> On 31 May 2011, at 22:31, Voll, Toivo wrote:
>> Netalyzr ( finds no
>> issues with my IPv6 status, but alerts me to the fact (since
>> confirmed by switching to IE) that Google Chrome defaults to IPv4
>> rather than IPv6, and consequently a lot of the testing tools claim
>> that my IPv6 is broken.
> I'm a little confused there - the current Chrome prefers IPv6, and
> also now includes code to allow fast failover to IPv4 in the event
> IPv6 connectivity is down/slow (300ms headstart).
> I had some issues with Netalyzer detecting my dual-stack status,
> which the chaps there are helping with.

Netalyzer is Java-based, thus it uses the Java stack and not the
Javascript/ECMAScript stack that Chrome provides. As such it just
bypasses all of that and the coolest thing is that you might not even
have an IPv6-capable Java stack for your host.

The 1.6.0_25-b06 Oracle/Sun version on Windows that I have here seems to
do IPv6 just fine btw in combination with Netalyzr.

Apparently in my home case I have a slow DNS lookup (odd, never had
issues with that, maybe it has to do with me having to click 'accept' on
the windows firewall UI ;)

It takes 239 ms for your computer to fetch a response from our test
server using IPv6, while it takes 7289 ms for the same host to fetch a
response using IPv4 from the same server.

Definitely has to do with clicking 'ok' on the firewall button ;)


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