# File ../../auditor/lib/kasp_auditor/key_tracker.rb, line 348
    def check_inuse_keys_history(key_ttl)
      # Error if a key is seen in use without having first been seen in prepublished for at least the zone key TTL
      # Remember not to warn if we haven't been running as long as the zone key TTL...
      if (Time.now.to_i >= (@initial_timestamp + key_ttl))
        # Has a key jumped to in-use without having gone through prepublished for at least key_ttl?
        # Just load the cache from disk again - then we could compare the two
        old_cache = load_tracker_cache(false)
        @cache.inuse.keys.each {|new_inuse_key|
          next if old_cache.include_inuse_key?new_inuse_key
          next if (new_inuse_key.sep_key?) # KSKs aren't prepublished any more
          old_key_timestamp, old_key_first_timestamp = old_cache.include_prepublished_key?new_inuse_key
          if (!old_key_timestamp)
            @parent.log(LOG_ERR, "Key (#{new_inuse_key.key_tag}) has gone straight to active use without a prepublished phase")
            next
          end

          if ((Time.now.to_i - old_key_timestamp) < key_ttl)
            @parent.log(LOG_ERR, "Key (#{new_inuse_key.key_tag}) has gone to active use, but has only been prepublished for" +
                " #{(Time.now.to_i - old_key_timestamp)} seconds. Zone DNSKEY ttl is #{key_ttl}")
          end
        }
      end
    end