# File ../../auditor/lib/kasp_auditor/key_tracker.rb, line 241
    def process_key_data(keys, keys_used, soa_serial, key_ttl)
      update_cache(keys, keys_used)
      if (@last_soa_serial)
        if (compare_serial(soa_serial, @last_soa_serial) == 1)
          @parent.log(LOG_ERR, "SOA serial has decreased - used to be #{@last_soa_serial} but is now #{soa_serial}")
        end
      else
        @last_soa_serial = soa_serial
      end
      @last_soa_serial = soa_serial
      run_checks(key_ttl)
      # Then we need to save the data
      save_tracker_cache
    end