Getting the name of responding server(s)

[Stephane Bortzmeyer]

On Tue, Sep 07, 2021 at 12:33:59AM -0700,
 Ronald F. Guilmette <rfg at tristatelogic.com> wrote 
 a message of 33 lines which said:

> My question is rather a simple one.  Given some FQDN `D' and given
> some DNS record type 'T' (e.g. either A or AAAA or perhaps even PTR)
> does there exist some open source command line tool that can tell me
> the names of the DNS servers to which the final authority for
> answering a query about the tuple (D, IN, T) is delegated?

T is irrelevant since delegation does not depend on the type.

> I know that I can get this information by using "dig +trace", but that seems
> to be rather slow to me (wall clock time), and I want to be doing
> this a lot.

The only solution is chasing the delegations from the root (which is
what dig +trace is doing). Caching speeds it, this is why it is
better to go through your resolver than using dig +trace.

> So, does anyone know of an open source command line tool that can do just
> that, preferably quickly?

I'm not aware of a tool (free software or not) which does it. Some
programming will be required.