257. [bug] The server detached the last zone manager reference
too early, while it could still be in use by queries. This manifested itself as assertion failures during the shutdown process for busy name servers (RT #133). 256. [func] isc_ratelimiter_t now has attach/detach semantics, and isc_ratelimiter_shutdown guarantees that the rate limiter is detached from its task. 255. [func] New function dns_zonemgr_attach().