Stub Zone
A small DNS zone that contains only the NS and glue records for a parent or peer zone, used to short-circuit referrals.
A stub zone is a minimal zone configured on a recursive or authoritative nameserver that holds only the NS records (and any required glue) for another zone. It does not hold the actual data of that zone. The point is to short-circuit the normal delegation walk: a resolver with a stub zone for `internal.example.com` knows the authoritative nameservers for it directly, without having to ask the root or `example.com` parent. Microsoft DNS and BIND both support stub zones; they are common in split-horizon and Active Directory deployments.