are configured with different versions of the same zone, each separate
version uses the same set of signing keys.
+If the expected key files that were previously observed have gone missing or
+are inaccessible, key management is halted. This will prevent rollovers
+from being started if there is a temporary file access issue. If his problem
+is permanent it will eventually lead to expired signatures in your zone.
+Note that if the key files are missing or inaccessible during :iscman:`named`
+startup, BIND 9 will try to generate new keys according to the DNSSEC policy,
+because it has no cached information about existing keys yet.
+
The :any:`dnssec-policy` statement requires dynamic DNS to be set up, or
:any:`inline-signing` to be enabled (which is the default for DNSSEC zones).