freebsd: don't use `-f' in hostname
-if a zone doesn't change, don't bump the version
-BIND9: options
-BIND9: `bak' must be owned by the bind user
-
-empty zone for 254.169.in-addr.arpa. (RFC 3927)
+DNSSEC:
+- DS records and dependencies on them
+- NSCVER macro