Using RRL to for TC=1 on all queries

Tony Finch dot at
Sun Jun 20 14:19:09 UTC 2021

John Kristoff <jtk at> wrote:

> Has anyone configured BIND to force TC=1 responses on all queries using
> RRL?    I'd like to do this for some experimentation and measurement
> work, but maybe this just isn't the right tool for that job?
> I've tried a number of configurations (e.g. slip=1, rate=0) and I can't
> seem to make this work.  Perhaps it is not possible.

As far as I know, RRL will only truncate responses that exceed the limit,
and the minimum limit is 1. (Zero is interpreted as no limit.) So RRL will
leak at least one non-truncated response per second.

RPZ has a tcp-only action which truncates UDP responses, so if you set up
an RPZ that matches everything, that should allow you to do what you want.

f.anthony.n.finch  <dot at>
Shannon, South Rockall: Northeasterly 5 or 6, occasionally 7 in
Shannon. Moderate or rough. Showers at first. Good.

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