Background: Let's say I have a friend whose website, friend.example.net, is hosted by a hosting company at example.com. Whenever I try to reach friend.example.net, it redirects me to example.com. After some investigating, it turns out this is because of IPv6: the DNS resolves to both a v4 and v6 address, the browser picks v6, and it bugs and redirects me incorrectly (over http 301, "moved permanently" for crying out loud -- now this gets cached).

Problem: Now I need to explain to the friend that his website has IPv6 and that it bugs so that he has some idea of what's going on (and what the impact is for customers), and so that he can explain the problem to his hosting company.

Problem #2: Turns out that even the hosting company never heard of IPv6 (seems like one of these companies that try to do design, programming and server management all by one or two persons), which is really stupid but there is nothing to do about it in the short term, so I need to explain it to them too.

Question: How do I explain to them what IPv6 is so that they have a concrete idea of what's going on? The friend is curious what is wrong with his website, but beyond that doesn't really care about internet protocols. And although he needn't know really, I'd like to give him some idea instead of telling him that he needn't know. And the guy at the hosting company should of course speak to whomever configured the servers, but if that's himself he should be able to effectively google more info to solve it.

So what things should I mention? E.g. that it's an ISP thing, or that the previous version is running out of addresses and we're slowly switching, or...

Something I came up with on the spot (when the friend asked) was that it's some sort of new version of the internet, which it is, but in hindsight people usually don't have any idea what the internet is exactly and what a new version might mean, so it's a useless thing to say. It seemed to make him think it was some sort of operating system, but explaining that it is something the ISP does (e.g. Verizon or, in the example, example.com) seemed to clear up that it's not something on my computer.

And as for the hosting company, I have no idea how they managed to configure their services in a way that causes this behavior. Their site's headers tell me they're running Ubuntu with Apache 2.2.22, and Apache will just listen on :: and if you tell it to, then treat vhosts for either IP version alike. The vhost for friend.example.com will result in the same website over v4 as over v6, as far as I know. So I don't know what they did and I can't give pointers on how to remedy it. But then what should I tell him instead? Another "new internet version" story is probably as ineffective here as it was with the friend.

  • possible duplicate of What's a good IPv6 tutorial? – Ƭᴇcʜιᴇ007 Jan 23 '14 at 14:14
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    You don't need to explain IPv6 to the hosting company. You need to explain to your friend that the hosting company is utterly incompetent. – Michael Hampton Jan 23 '14 at 17:39
  • @techie007 I've seen that one, but I'm not looking for a tutorial. I'm trying to explain IPv6 very briefly to someone who has no concept of what the internet is made of. In fact I've written an IPv6 tutorial myself, but it's pretty long and way too much information to tell someone in a normal conversation. – Luc Jan 23 '14 at 19:15
  • @MichaelHampton It's one of those great deals where the hosting comes with the design. "Want to change hosting? Build yourself a new website." Note that I didn't know at the time, I would have told him it was a bad deal. – Luc Jan 23 '14 at 19:22

We need some identifiers (IP addresses) to distinguish computers on the Internet. We're moving to IPv6 because we ran out of possible IPv4 addresses.

Your server has two IP addresses: the old IPv4 address and new IPv6 address. DNS is an addressbook of the Internet. When somebody asks

Hi, where can I find www.example.com?

the DNS replies:

Look for if you like IPv4 or 2001:db8:1:: if you prefer IPv6.

The browser chooses IPv6 because it's the preferred standard. But your server is misconfigured - you can connect to it under its IPv6 address, but when somebody asks it:

Hi, DNS told me that you are 2001:db8:1::.

it will reply:

No, my only address is But you should really check out our hosting provider's website. It's hosting.example.com.

And that's it.

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    And they lived happily ever after ... – Vorac Jan 29 '14 at 12:38

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