Jim Rees <rees@xxxxxxxxx> wrote: > > Would this be the same as NXDOMAIN? That is, does it mean the name server > > couldn't find a record, or does it mean that the record doesn't exist? > > Is there a way to tell the difference? Can you store a negative record in > the DNS? Or is it that the DNS has records for the name, just not records > of the type you're looking for (eg. NO_ADDRESS/NO_DATA from > gethostbyname())? > > It's an important distinction to the resolver if you want to avoid dns > hijacking. See rfc2308. There doesn't seem to be a way to tell the > difference from the gethostbyname call, which was designed before this was a > problem. The on-the-wire dns query protocol does make the distinction. > > I suspect kernel dns clients won't need to know the difference, but I think > it's useful if we decide on and document the meaning of the error codes. > Maybe the answer is that ENAMEUNKNOWN means the same as a HOST_NOT_FOUND > from gethostbyname(). Should I propose an extra error code? Perhaps giving: ENONAMESERVICE "Network name service unavailable" ENAMEUNKNOWN "Network name not known" ENONAMERECORD "Network name query returned no records" Note that ENONAMESERVICE covers all of: not having a name service configured, not being able to contact the configured name server and the configured name server not being able to chain to the authoritative name server. However, I think this is probably okay. David -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
