Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)

Ted Lemon <> Wed, 06 January 2021 17:10 UTC

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From: Ted Lemon <>
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Subject: Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
Date: Wed, 6 Jan 2021 12:10:26 -0500
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Cc: Gert Doering <>, IPv6 Operations <>, Philip Homburg <>,
To: Fernando Gont <>
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On Jan 6, 2021, at 11:46 AM, Fernando Gont <> wrote:
> I have Raspberry Pis that deploy here and there. In order to be able to access them, they use dynamic DNS to post their addresses on their DNS.
> If I don't look at the properties of the addresses, then I end up puting crap on the DNS. One straightforward consequence is that many apps that don't do Happy Eyeballs end up having an insane connection-establishment period, if they happen to try the unusable addresses first.
> So "find all your IPv6 addresses and post them to the DNS" doesn't work.

It is of course not even obvious how to solve this, because sometimes you do want ULA in DNS, and sometimes you don’t. And it depends on what DNS. If you are doing split DNS, then you can scope the DNS that advertises ULAs only to serve those networks where those ULAs are in-scope. The DNS that is advertised globally would of course contain no ULAs. How this is arranged is either a matter of local configuration or an interesting topic of future work, depending on how you look at it.