Extended DNS Error (EDE)
Extended DNS Error (EDE) is an EDNS0 option, defined in RFC 8914, that lets a DNS server attach a machine-readable numeric code and short text to a response explaining why it answered the way it did, rather than leaving a client to guess from a bare SERVFAIL or NXDOMAIN. Codes distinguish causes that previously all looked identical from outside -- a DNSSEC signature that's expired (code 6), a name blocked by local policy (code 15), or a forwarder unable to reach its own upstream (code 22) -- so a filtering or validating resolver can report the actual reason instead of an opaque failure. This matters most for resolvers that intentionally withhold an answer, such as a DNSSEC-validating resolver rejecting a forged response or a protective DNS service blocking a known-malicious domain, where EDE turns a bare failure into a reason an administrator can actually act on.
By AdminKit team, Netbase JSC · Updated