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Why does windows seemingly randomly use or not use IPv6 on the *same* sites?
Hello,
After getting my GoGoNet tunnel working, I found a handy Firefox add-on called "ShowIP", which I've been running, so that I can see when a site I visit has IPv6 enabled.
I've noticed something strange though. Sometimes, when I got to a website, I'll get an IPv6 address showing as being used by Firefox, and sometimes if I go back later, an IPv4 address - for the same site!
For example, I've noticed this with Google.com - NOT ipv6.google.com, but just plain old google.com - sometimes when I go there, it uses IPv4, sometimes IPv6 - why would it switch back and forth like that?
I believe I've noticed the same behavior with the blogging site blogspot.com. There's a number of blogs I've been visiting on blogspot lately, and I could swear that sometimes it uses an IPv6 address, and sometimes IPv4.
Anyone able to shed some light on this mystery?
I'm using Firefox on Windows Vista (32-bit). IPv6 seems to be working fine - using "ping -6" to ping an IPv6 enabled website works, and usually I can omit the -6, because it'll just default to using IPv6 most of the time.
After getting my GoGoNet tunnel working, I found a handy Firefox add-on called "ShowIP", which I've been running, so that I can see when a site I visit has IPv6 enabled.
I've noticed something strange though. Sometimes, when I got to a website, I'll get an IPv6 address showing as being used by Firefox, and sometimes if I go back later, an IPv4 address - for the same site!
For example, I've noticed this with Google.com - NOT ipv6.google.com, but just plain old google.com - sometimes when I go there, it uses IPv4, sometimes IPv6 - why would it switch back and forth like that?
I believe I've noticed the same behavior with the blogging site blogspot.com. There's a number of blogs I've been visiting on blogspot lately, and I could swear that sometimes it uses an IPv6 address, and sometimes IPv4.
Anyone able to shed some light on this mystery?
I'm using Firefox on Windows Vista (32-bit). IPv6 seems to be working fine - using "ping -6" to ping an IPv6 enabled website works, and usually I can omit the -6, because it'll just default to using IPv6 most of the time.
Views: 358
Replies to This Discussion
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Permalink Reply by Carl Holzhauer on -
My first reaction is that your IPv6 connection is somehow timing out. This could be caused by slow IPv6 access times *tunneling is always slower than native access)
What are you using for your DNS servers? By default, Google will not respond to IPv6 requests. More interestingly, how did you get to blogspot over IPv6? A lookup only shows them as having an IPv4 address
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Permalink Reply by Jeff S. on -
"What are you using for your DNS servers?"
Well, the GoGoClient automatically configured a DNS Server for the IPv6 tunnel, at an IPv6 Address. Additionally, I have DNS Service from my ISP (IPv4 based), and a secondary/fallback server for IPv4 at 8.8.8.8 (which IIRC, is Google DNS).
I have no idea, exactly, whether Windows always uses the IPv6 DNS Server first/preferentially, then falls back to the other servers, or if it is using one of the other servers most of the time. Is the some way to figure that out?
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Permalink Reply by Carl Holzhauer on
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What's the address of the server that the GoGo6 client added? It's probably a GoGo6 DNS server, and IIRC, they're a Google partner for the IPv6 thing, so you would get a IPv6 google page.
Vista and newer prefer IPv6 over IPv4, so it will always ask the IPv6 DNS server before the IPv4 DNS server. You can check this by opening a command prompt and typing "nslookup" and seeing which DNS server you're pointed at.
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Permalink Reply by Jeff S. on
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The GoGoClient configured DNS Server is: 2001:5c0:1000:11::2
Last night, Google was showing an IPv6 address when accessed with Firefox, and now this morning, Google is showing an IPv4 address. I can't seem to get the blogs which showed IPv6 addresses to use IPv6 this morning - they are all showing IPv4 addresses.
UPDATE: If I close Firefox, then use the nslookup command to lookup www.google.com, it returns an IPv6, then after that, if I open firefox again and go to google, it uses the IPv6 connection instead of IPv4. As for the Blog, nslookup returns an address of:
2a00:1450:8002::84
However, Firefox keeps using the IPv4 address to connect this morning. It's rather puzzling.
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Permalink Reply by Carl Holzhauer on
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Yeah, that DNS server is from GoGo6
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Permalink Reply by Mikael Lind on -
I've also seen this behavior on win 7. It happens when windows uses different DNS servers for different queries as google is only available on v6 on the gogo6 DNS. On my machine it seems it prefers the IPv6 DNS most of the time but not always.
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Permalink Reply by Jeff S. on
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Could this be a race condition? I'm wondering if Vista might just fire off a packet to every listed DNS Server, then use the answer from whoever responds first?
In any case, does GoGoClient have any capability to 'disable' the other DNS Servers, temporarily, while the tunnel is established, then automatically restore the IPv4 DNS if the tunnel is disconnected? The thing is, I need the IPv4 DNS, if for no other reason than that GoGoClient needs to query IPv4 DNS to resolve the authentication and gateway servers for setting up the tunnel.
Seems like, once the tunnel is established, the IPv4 DNS servers could be disabled, couldn't they?
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Permalink Reply by JC John Sese Cuneta on
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Based on my testing before, Firefox doesn't refreshes its IPv4/6 priorities. If you have Firefox running (check in the background also) before GoGo6 successfully connected, Firefox will use IPv4. Then if you restart Firefox, sometimes it updates, sometimes it doesn't.
The best way for Firefox is to wait for GoGo6 to connect successfully then launch Firefox. The best way to test if your browser is prioritizing IPv6 or IPv4 is to visit http://ip6.me
ip6.me is by default checks IPv6 first before IPv4. If your browser returned a 'success' IPv6 connection, IP6.me will show it. If not, then your IPv4 address will be shown instead.
That testing site have plenty of URLs, all of those defaults to IPv4 so use only ip6.me (as in type it in your browser http://ip6.me).
(You will also notice here that teredo/miredo is not higher in priority than IPv4, even in Linux. You can have a teredo/miredo IPv6 but your OS prioritizes IPv4. So if you have it activated, don't be alarmed, it is normal.)
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