unbound fails to do reverse look ups

[Carlo Wood]

Hello Jan,

thank you for your reply!

Why would any firewall go so far as to specifically filter on DNS
queries with certain flags?! I didn't even know that was possible :/.

Could this be done by my ISP? If so, is there a way I can find out
where exactly this filtering happens? I am using a Linksys Router
that still has the firmware of VPNExpress on it, even though I no
longer have an account there. I suppose that theoretically it is
possible that even my own router does this, because DNS (leakage)
is a VPN thing - if that is the case then I want to switch back to
opensource firmware... In that case the closing of the connection
should be sub-millisecond I think. I wonder if I can measure that
easily?

Carlo

On Fri, 17 Oct 2025 21:22:24 +0000
"Jan Komissar (jkomissa)" <jkomissa at cisco.com> wrote:

> Your result may be caused by a misconfigured firewall that
> drops outgoing DNS queries without the recursion flag set.