Reverse name lookups returned nothing for the whole network

Looking up a name from an address — the reverse of a normal lookup — returned nothing for every address on the network, from both resolvers.

This is the lookup that turns an address into a readable machine name, so logs, monitoring output and diagnostics showed bare numbers where they should have shown names.

Cause. The forwarding was configured correctly, and had been for some time, but a single setting that governs whether the resolver consults those forwarders for private addresses was switched off. With it off the resolver answers “no such name” immediately and never asks. The configuration looked complete, which is why it survived earlier checks.

Fix. That setting is on, applied to the resolver the other one copies from so it cannot be reverted by the next sync. Verified from both resolvers, with normal lookups and filtering unaffected.

Status: resolved and verified.