Consider the following scenarios:
- When a Windows Server 2012 R2-based DNS server is enabled for domain name system security extensions (DNSSEC) validation, the DNS server may not always resolve some DNSSEC-signed zones. For example, when the DNS server receives a request to resolve a host name in a DNSSEC-signed zone, the DNS server returns a SERVFAIL error to the client.
- A server that is running Windows Server 2012 R2 is used as an upstream forwarder for DNSSEC queries. In this case, when the Windows Server 2012 R2 forwarder DNS server does not receive DNSSEC records in a certain order, it cannot cache the full record list, and replies to the validating DNS server are incomplete. This causes DNSSEC validation to fail. This behavior occurs when a BIND server is used to return DNSSEC records to the Windows Server 2012 R2 forwarder.