I've pushed to sources changes to ndb/dns intended to improve the effectiveness of its caching. Thanks to Dave Presotto for locating the specific problems.
I've also attempted to make dns's diagnostics in /sys/log/dns more specific, to pinpoint the client sending bad requests and to detail the errors in the requests. Some of the diagnostics are still somewhat cryptic; I plan to improve them as we get more experience with them. Some errors characteristic of MS Windows are detected and not logged to avoid filling the logs with complaints about systems that cannot be fixed (except by an OS upgrade). Seriously misformatted DNS requests now draw replies with error flags set, so clients at least get feedback that they are in error. dns processes now have their names (visible with ps -a) set to indicate what they are doing. The internal %R formatting code is now more robust against incomplete Req structures being printed. ndb(8) has been updated to reflect all this and had its formatting slightly altered to improve legibility.
