ServerFailedException ends ExtendedResolver resolution

[nathankurtyka]

Shouldn't a ServerFailedException simply invoke the next SimpleResolver? Currently, a (possibly transient) DNS error response seems to be irrecoverable.

Or is there a workaround I'm not seeing?

[ibauersachs]

Sorry for not getting back to this earlier.

ServerFailedException is created from a SERVFAIL response in LookupSession, regardless of the used resolver. If you're using a SimpleResolver this naturally ends the lookup.

For ExtendedResolver, well, good question. A SERVFAIL response is not a network error and thus is considered a completed lookup. I guess there could be a (new) option added to ExtendedResolver that continues on SERVFAIL responses.