something to trace lookup recursion?

[Phil Howard]

I'm looking for a way to, starting from the top, perform a recursive lookup
of a name, going all the way to authoritative records (A, MX, and PTR, in
particular), with a trace log of every step along the way.  For most things
this would list the root servers, and the ISP DNS servers, and finally the
data.  But it would need to handle whatever situation there might be, even
CNAME references.  The big thing is I need to extract a list of all the DNS
servers that are involved in the given name, and a little bit of information
about them (what level and what role).

My guess is that I could do this with "dig" by applying a script around it,
specifying +norecurse so the servers don't do anything extra for me that I
don't know about, and just following through the NS and CNAME records in the
appropriate way (for other reasons I only need to follow one NS record when
there are usually more than one).

Before I delve into the design of such a thing, which would involve parsing
the zone data from "dig", I thought it best to ask first so as to avoid
re-inventing the wheel.

Has anything like this already been done?

-- 
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