Hi,

In summary, my question is whether there is a way to configure a bind caching 
server to provide recursion in response to iterative queries for records in a 
forward type zone.

The background is that we have:

- AD domain controllers that are authoritative for all of 10.in-addr.arpa. in 
our data centers - most clients point to these for DNS resolution.
- Linux bind caching resolvers in our data centers - domain controllers forward 
to these for anything they don’t own.
- Some AWS VPCs which have been allocated subdomains of 10.in-addr.arpa. and 
are routable from our data centers. These have Route53 inbound endpoints which 
answer queries for those subdomains.
- The bind caching resolvers have forwarding rules for those subdomains to the 
AWS inbound endpoints.

The subdomains in our AWS VPCs have NS records, but the servers those point to 
refuse queries for records in the subdomains. The zone resolution is taken care 
of by the Route53 resolver service. The Route53 inbound endpoints successfully 
resolve queries from our data centers for those subdomains as long as the 
recursion desired flag is set to 1 in the query. If recursion desired is set to 
0 they do not send any reply at all.

We want to be able to resolve PTR records in the subdomains in the AWS VPCs 
from our data centers where, as I said above, the clients point to the domain 
controllers for DNS resolution.

Because the AD domain controllers already own 10.in-addr.arpa, they refuse to 
allow us to configure conditional forwarding for its subdomains. So we 
delegated the subdomains to the inbound endpoints. Because they are 
delegations, the domain controllers set the recursion desired flag to 0 on the 
queries they send to the endpoints, and we are not getting replies from the 
endpoints.

As a workaround we tried delegating to our linux bind caching resolvers but we 
ran into the same issue, that the domain controllers set recursion desired to 
0. As a result, when our linux caching servers have the result in cache, the 
lookup is successful, but when it would require a fresh lookup it gets a reply 
with no answers. Hence my question, is there a way to tell our bind caching 
resolvers to ignore the recursion desired flag and provide recursion anyway?

Thanks,
Maria
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