Aggressive DNSSEC Caching Reuses Authenticated Denial Proofs
A conventional DNS negative cache remembers a negative result for a specific query. DNSSEC adds richer material to that response: NSEC and NSEC3 records can cryptographically prove that names or record types do not exist. RFC 8198 permits a validating resolver to reuse those cached proofs for later queries that fall inside the proven space. This behavior is called aggressive use of the DNSSEC-validated cache. It can suppress repeated authoritative lookups for names whose nonexistence is already established by validated data. The mechanism is more than a performance optimization: fewer unnecessary queries also reduce exposure of misspelled or random names beyond the recursive resolver and can absorb part of the load created by random-QNAME traffic.