Forward-zone & NS delegation not working as expected

We're seeing the following problematic behaviour (with 1.3.4):

a)
forward-zone:
  name "domain.tld"
  forward-addr: a

b)
there exists sub.domain.tld - a DDNS subdomain with active directory
stuff. When querying a for "sub.domain.tld", it returns IN NS records
pointing to servers x, y, z.

c)
when querying for host.sub.domain.tld, the request does NOT get sent to
x, y, z by unbound but gets forwarded to a (which does not know how to
answer the request).

The workaround is currently to setup
forward-zone:
  name "sub.domain.tld"
  forward-addr: x
  forward-addr: y
  forward-addr: z

but that's annoying as the actual nameservers returned by a for
sub.domain.tld change sometimes, which means having to change the
unbound forward config.

Our old dnscache setup handled this configuration out of the box without
special forwarding rules for the more-specific sub.domain.tld

any thoughts?

Kind regards,

Felix

* Felix Schueren:

We're seeing the following problematic behaviour (with 1.3.4):

a)
forward-zone:
  name "domain.tld"
  forward-addr: a

Shouldn't you use a stub zone instead? Has domain.tld got a
meaningful NS RRset?

Yes a stub-zone for sub.domain.tld is what you need to configure.
stubs under a forward zone did not work but this was fixed (recently).

Best regards,
   Wouter