[dns-operations] SERVFAIL or REFUSED?

[Niall O'Reilly]

Hello.  Clue needed, please.

I thought I knew, or at least knew where to find out, which status
should be returned by a name server which receives a recursive query
but doesn't do recursion either at all or for the part of the network
where the originating client is.

I think it should always be REFUSED.  I've seen this as well as
SERVFAIL in the wild.  Is either equally acceptable, or is only one
strictly correct?

TIA and VBR,
Niall O'Reilly