Log more detail when IXFR fails with 'failed while receiving responses: not exact'
There are actually two things that it would be helpful to log:
- When the zone update fails, what is the exact scenario was that caused the failure (including the RRs involved).
In this specific instance, it was a duplicate add, generated erroneously by a registry application, but not knowing why the zone update failed made the troubleshooting much more difficult.
- Leading on from 1, it was discovered that while named will fail to accept an IXFR'd ADD that is a duplicate when this arrives in a new incremental update, it will ignore duplicate ADDs that are part of the same incremental update. This was somewhat of a surprise, and which also contributed to the difficulty troubleshooting (because 'we know there are occasional duplicates, but they don't usually cause a problem').
Therefore, if named is going to silently discard some duplicate adds, it should at least log that it did so!