The “FAIL” result in the Delegation (Del) test typically indicates that the parent DNS zone does not contain a proper delegation record pointing to your child domain’s authoritative DNS servers. To resolve this, please verify that the parent zone includes the correct NS records and that those records reference the valid IP addresses of your domain controllers. Additionally, ensure that the DNS servers hosting the parent zone can successfully resolve queries for the child domain. If you are using Active Directory–integrated DNS, confirm replication is healthy and that all domain controllers are properly registered. Running dcdiag /test:DNS /v can provide further diagnostic details to pinpoint misconfigurations.
I hope this helps clarify the issue and guide you toward a resolution. If you find this answer helpful, please don’t forget to click “Accept Answer” 🙂.
Harry.