An entity acting in the role of a name server that understands the DNS security extensions defined in this document set. In particular, a DNSSEC-aware name server is an entity that receives DNS queries, sends DNS responses, supports the EDNS0 [RFC 2671] message size extension and the DO bit [RFC 4035], and supports the RR types and message header bits defined in this document set.
Sources:
NIST SP 800-81-2