o listen to NOTIFY messages for zones and flush the cache for that zone
if received. Useful when also having a stub to that auth server.
Needs proper protection, TSIG, in place.
+o winevent - do not go more than 64 fds (by polling with select one by
+ one), win95/98 have 100fd limit in the kernel, so this ruins w9x portability.
*** Features features, for later
* dTLS, TLS, look to need special port numbers, cert storage, recent libssl.
not create packet storms with operator errors.
o on windows version, implement that OS ancillary data capabilities for
interface-automatic. IPPKTINFO, IP6PKTINFO for WSARecvMsg, WSASendMsg.
-o winevent - if many fds, poll them with 100ms timeout.
o local-zone directive with authority service, full authority server
is a non-goal.
o infra and lame cache: easier size config (in Mb), show usage in graphs.