This isn’t currently deployed, but by self-hosting the authoritative nameserver 
(rather than using Cloudflare), we could observe per-attempt wildcard DNS 
queries (e.g. <timestamp>.<fingerprint>.tor.exit.validator.1aeo.com) and 
correlate whether those queries reach the authoritative server when initiated 
by exit relays.

When comparing exits within the same IPv6 /64, we would expect to see one of 
three outcomes:

1) queries arrive directly from the exit IP (recursive resolution)

2) queries arrive via a shared upstream resolver

3) no queries arrive at all, which would be consistent with resolver-side or 
upstream /64-level blocking

Implementing this requires some additional work, so it would be useful to 
understand how commonly exit operators encounter suspected /64-level DNS 
blocking in practice.



On Saturday, January 17th, 2026 at 3:46 PM, forest-relay-contact--- via 
network-health <[email protected]> wrote:

> 

> 

> Hello.
> 

> Tor at 1AEO wrote:
> 

> > - Classifies failures: timeout, NXDOMAIN, wrong IP, SOCKS errors
> 

> 

> Would this be capable of detecting whether or not nameservers block the
> entire /64 that an IPv6 exit is on? I've always been concerned about
> enabling IPv6 in Unbound with the fear that, even if the IP differs, it
> would still be blocked due to being in the same /64.
> 

> For IPv4, the solution is expensive but easy: Buy a second IP. For IPv6,
> it would be really nice if I didn't have to buy a second /64.
> 

> Regards,
> forest

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