> Also, that cache would need to only kick in when the server was unreachable or produced SERVFAIL, not when it returned a negative result. Negative results ret

> Also, that cache would need to only kick in when the server was unreachable or produced SERVFAIL, not when it returned a negative result. Negative results returned by the authoritative server are correct, and should not result in the recursive resolver returning anything other than a negative result. Precisely. I am not suggesting any change to how a caching resolver comprehends valid responses from the authoritative server for a domain. For example, if the authoritative server says, "No such domain," then the domain is understood to be gone. At that point, the domain being gone is in fact the last-known-good resolution.